Is this possible? What gods or spirits can help? Can you do this without them?
Yes and this kind of magic is strongly associated with Vampyrism and central to my own work. It is intrinsically Left Hand Path because it is not surrendering to fate but consciously trying to intervene/reverse it. More on fate in a moment.
It does not depend on gods, you need never work with them at all, but invoking selectively (closer to plugging into an egregore or totem for your work than traditional religious approaches) can help. "Spirits" are useless for this kind of work. In terms of gods, those strongly associated with the Vampyre tradition work best: Ishtar, Dionysus, Freyja, Satan, even calling on the Vampire as archetype - all of these forces traffic in these forms of intensity.
What is needed are sources of replenishing energy. This can come from treating your body with healthy and life-giving foods, drinking enough water and getting exercise. That will change your body which will, in turn, give you access to greater levels of energy which then need to be transmuted towards renewal. One powerful way of doing this is to undergo new experiences. The brain associates new experiences, opening new neural pathways, with youth because, in their first twenty-five years, most people do most of their learning. When the brain is forced into new experiences all the time, it will respond as it did in youth, as it always does, releasing a flood of hormones into your bloodstream (another reason why good diet and exercise are important). The more visceral these new experiences are the better - try sky diving, sleeping outdoors, for really potent influxes, though a new kind of film or trying something outside of your comfort zone will also work.
In times of dire need, you can use what Anton LaVey called Erotic Crystallization Inertia (ECI). This means turning towards aesthetic inputs (music, decor, films, etc.), which you associate with your own puberty or times of high sexualisation. This will release energy which those things have stored for you. Use this technique sparingly though. Unless it's an extremely powerful form you can wear it out. Say, if a song reminds you of being thirteen, you will get a release of energy through hearing it again but if you overplay it, the association will shift from when you were thirteen to now.
In the final analysis we cannot escape from the fates entirely. One day our body will break down and die. What we can do is alter the parameters of time and what things look like within that time. Like Odin knew, we must surrender to the fates in the end but, while we can, it doesn't mean we shouldn't try to avert them.