Not a spell, per say (I'm pretty sure I misspelled that). Reincarnation is a spiritual or religious belief with plenty of contradictions. For instance, Buddism sees reincarnation as (based on what I have read) a continuous cycle of suffering we endure until we spiritually evolve beyond it and achieve nirvana. Hinduism, meanwhile, believes in karma, where our actions in this life determine what our next life will be. I personally believe that prior to incarnating (while we are dead), we map out our life as we wish to live it (it's a very basic outline, so we still have plenty of free will in this life). You can, in theory, decide what life you would like to live next while in this life. I think that you should trust yourself that you chose this life for a reason, but that it is still your life to live and you can live it however you want. Before you ask, the only person that can answer why you choose this life is you.
* per se. And no you can't, as the post before me said. It is a belief thing, there is no proof that it actualy happens. I believe that it does, as with out a small bundle of information it would be hard to survive a year of birth. Also have you ever got the feeling that you know how to do something that you gave never even heard of before? I believe this to be the reason.