Our Infinite Fates by Laura Steven

Evelyn – or Branwen Blythe – can remember all her past lives. She can also remember that in every single one, she’s been murdered before her eighteenth birthday.

The problem is that she’s quite fond of the one she’s in now, and more importantly, her sister needs her for bone marrow transplants to stay alive. So now she has to:

1. find the centuries-old enemy who hunts her through each life and destroy them forever
2. figure out exactly why she’s being hunted in the first place,
3. try quite hard not to fall in love with them

…again.