If you're looking for something like, "Take XYZ materials and follow step one, step two, step three" like stick a chunk of moonstone under your pillow or something... Sorry, I'm personally more of the opinion that it's not the spell that does it but the spellcaster. This particular case requires mental discipline and the cooperation of the subconscious, which I believe spells depend on , so there is no spell to bring it about .
Meditate, meditate, meditate is all I keep advising and the only thing that I will advise. Since you've posted about having dreams about your past life anyway, I can only recommend that you write them down and meditate on what you remember when you have the time.
There's a method called lucid dreaming where you'll be able to retain your waking life memory and waking life reasoning in the dream, and it can come about spontaneously simply by your reading that this is possible. Or, you can meditate while you're waiting to sleep and allow the dream visions to come to you.
Frankly, though, I doubt that lucid dreaming will work for you because it requires emotional moderation to sustain and you appear to be too anxious. In addition to memory and reasoning, lucidity requires balance and a clear goal. I think you're too frenetic right now to make this work. This needs to be a negotiation with the subconscious, and in my opinion you're approaching it with dominance like, "These dreams have to be clear and open about everything and make sense right the heck now and ASAP!!" That's understandable, from what else you've posted, but it's not actionable.
Working with dreams usually requires a knack for oblique suggestions, a willingness to let some things just come to you, and a high tolerance for ambiguity. I see none of these qualities in you, so I can only recommend that you give it time.