I am actually familiar with quite a few books with a similar theme or premise to ''Flip'', but there are very few which are as absorbing and believable as it. [[The Double Life of Cassiel Roadnight by Jenny Valentine]] has a protagonist in a similar situation to Alex, and comes highly recommended from TheBookbag. Meanwhile, [[The Returners by Gemma Malley|The Returners]] by the brilliant Gemma Malley is a fascinating exploration of free will and fate, with a supernatural edge in the form of reincarnation, which I would also recommend.