I honestly don't know. I don't think much about the afterlife or previous lives largely because it is irrelevant to how I live THIS life, right here right now. My Orthodox friends certainly believe in transmigration of the soul, but most of my Reform friends don't believe in a soul at all. Once a therapist told me I had an old, old soul, and strangely I just felt that this was reassuring and validating.
I certainly have had experiences which COULD BE interpreted as past life memories. But there are alternative explanations as well. For example, maybe I'm just a good "radio receiver" of the energy patterns left by other lives. Maybe my imagination is simply SO good, that it feels like a memory.
IF past lives are a reality, they likely give an unconscious push in certain directions, to complete what was incomplete, to right what was wrong. But I don't need to be conscious of those past lives in order for that to happen.
I'm fine just remaining an agnostic on this issue.