Elsewhere by Gabrielle Zevin

What do you imagine heaven looking like? What do you think we'll do there? This very original, young-adult novel takes these questions on.

Liz Hall ends up in heaven, or "Elsewhere," after she's hit by a car as a fifteen-year-old. She finds that Elsewhere is like earth, but instead of getting older, everyone is getting younger, until they become a baby again and are shipped back to Earth to start a new life all over again. 

Simply, but nicely written, this book is fun to read!