That's an interesting question. From my knowledge I can think of some of the possibilities:
1. Ars Goetia / Goetic Spirit Rituals
You can choose whatever ritual format you want: demonolatry, "Demons of Magick" (Gordon Winterfield), "Goetia Pathworking" (Corwin Hargrove), Ars Goetia, you name it. The point is to find a good ritual format to work with that fits your comfort and preferences to contact the spirit. My recommendation and goto has always been "Demons of Magick", but this is always your choice.
The next important part is the choice of spirit and what you will target to get passion / inspiration. For example, if you want to mentally change yourself to feel passion for something specific, then you can work with a spirit like Dantalion or maybe Paimon. Their abilities are oriented towards mental manipulation and change, so there is no reason why you shouldn't be able to that to yourself.
If you want to inspire passion for a particular skill or type of knowledge you are learning, then you could consider Asmodai or Vapula. Vapula is specifically a spirit who is capable of blessing your efforts to learn a new skill, which could manifest or be requested as getting more passion to learn it. Asmodai has a similar capability in that regard, but probably even more intensely.
Finally, you could consider a spirit like Astaroth who has 2 abilities which might be relevant to this. One is that Astaroth can help you find out what you really want to do in life. This is something that can obviously lead to inspiration and passion towards a deeply held goal or desire that could give you direction in life. This won't likely give you passion or inspiration in general, but towards a specific thing. The 2nd ability of Astaroth is to unleash a period of creative chaos in your life, which is how "Demons of Magick" puts it. I never petitioned for this capability directly, but I can imagine that "creative chaos" could refer to a lot of things. It sounds almost artistic when I imagine what creative chaos looks like, so this could lead to inspiration and passion if it is directed in the right way.
These would cover the Goetic spirits, but there are other ways.
2. Internal Alchemy
There is also the possibility to use internal alchemy to encourage this. By internal alchemy, I am not referring to stuff like Taoist spiritual alchemy or necessarily specific eastern energy work practices. Instead, I refer to the transmutation of character or personality traits within yourself. This line of thinking is especially present in Franz Bardon's work "Initiation into Hermetics". But the basic idea is to weaken the so called "negative" character traits within yourself and to transmute them to "positive" traits. We don't necessarily need to debate what counts as positive or negative, but rather consider how this can be applied to the question you are asking.
From your question, we can identify 2 positive traits: being filled with great passion and being inspired. And then we could consider their opposite "negative" traits: being totally dispassionate and being totally uninspired. If you find that you are actually already passionate and inspired, but wish for more, than consider the negative traits to be a lack of sufficient passion or inspiration. Either of these will work. But focusing on opposites is what works quite well for this approach, so in this case: dispassion / lack of passion and total lack of inspiration / disinterest.
In my experience, the best way to go about the "transmutation" process is to employ 2 separate processes. The 1st process is to have a way to remove or expunge the negative trait from yourself, which weakens the negative trait. The 2nd process is to have a way to add / augment the positive trait within yourself, which facilitates the replacement of the disappearing negative trait with something else (ie the positive trait). On the outside, this pretty much sums up to be changing the negative trait into the positive trait.
The work of Franz Bardon provides multiple methods to do this and his framework of practices is a big discussion by itself beyond the confine of what I can write here. I will focus on a few key practices that I readily use. For practices to remove negative traits, there are 2 I use primarily: the attractive power of the water element and the exhalation of the negative trait. For the addition of positive traits, you have the inhalation of positive qualities and / or the blessing of food / drink with the positive quality.
For the water element, all you need is cold water running down a sink and through your hands. You imagine the lack of inspiration or dispassion literally clinging to the water and being washed from your hands, which you can picture as black astral grime or just the feeling of un-inspiration or dispassion being washed away with the water. It is important to use cold water for this, with the colder being better. The theoretical side of this basically states that the water element is receptive and therefore "magnetic" in a sense, with the cold aspect of water being the magnetic side of it. So the colder it is, the better the water attracts the negative trait out of you. The main thing to know is that by imagining the removal of the negative trait being done with the water, your will is facilitating the selective removal of that trait from you and this is the important part. I usually do this for 2 minutes a day for 3 weeks to weaken the negative trait.
The next part concerns the breathe with the inhalation and exhalation of the positive / negative traits. The air around you can be "charged" with an intention or a desire. So in this case you can charge the air with an image or a thought of you being a passionate / inspired person and the air will hold on to that intention. When you breathe the air in, you will take that intention inside of you and the spiritual make-up of your astral body will absorb the intention out of the "astral" side of the air and this intention passes into your astral body. With enough repetition, that intention can build up in your astral body and over time manifest into the physical world through you. A similar idea can be applied for the air you breathe out - you imagine your dispassion / lack of inspiration as being attached to the air inside of you and you then breathe it out. You can literally imagine the image of dispassion leaving you via the air you exhale. For this, 30 breathes a day in / out with these dynamics for 3 weeks has worked well.
The final part is the blessing of food / drink with the positive trait. This works in the same sense as what you do with the air. The spiritual make-up of the food, water, or air is able to accept an intention inside of it, which you then take into yourself. You can literally imagine the image or feeling of passion within the food / drink and with an act of will believe that the food / drink is actually passion or inspiration. You are literally turning the spiritual make-up of the food / drink into the image and concept of inspiration or passion. Then you consume it and feel as if the positive trait is now being digested or pulled into your body. My preference is to imagine that once I have eaten / drank the thing, the trait is being pulled into me and I then consciously identify myself as embodying the positive trait. I do this with 1 glass of water and / or food item a day for 3 weeks.
You need to combine these methods together and repeat them for a good duration of time to really see the results. But even more importantly, you must not be passive about your intention. As with spirit based petitions, you must also provide a good means for the intention to manifest. In this case, you must actively try to seek inspiration and passion in the relevant parts of your life so that you can let the astral ground work of the transmutation more easily manifest into the physical world. But in my experiences, this is a powerful method that works if you apply it consistently and regularly.
3. Kabbalistic and angelic magick
The final method in my own toolkit that could work is using angelic magick derived from practical Kabbalah. The easiest work for this is the rituals found in the GoM book called "Angels of Alchemy" (Damon Brand). The rituals in there contact 42 angels that are capable of various targeted acts of transformation. For your case, I even think there is an angel for passion and another for inspiration that can specifically work on these aspects for you. The difference with the spirits of the Goetia is that the ritual method in this one is simpler, but you will need to experiment to find out which suits you.
But the basis of this work is the 42 lettered name of god found in practical Kabbalah, which is derived from the Ana Bekoach prayer. This prayer is a kabbalistic prayer, which is supposed to contain transformative power. It taps into the creative power of the divine and enables subtle spiritual change to take place when invoked and there are 42 angels associated with this prayer who embody the creative powers of the prayer. You may consider "The Book of Sacred Names" (Jacobus Swart) if you wish for a practical method to invoke the general powers of this prayer, but the direct work with the angels via the GoM book is the easier approach in my eyes. It is ultimately up to you. I do not have a lot of experience in this one beyond the book, as I have focused my efforts either on Goetic magick or the internal alchemy stuff.
