Before I Fall by Lauren Oliver
From the book blurb on Goodreads:
For popular high school senior Samantha Kingston, February 12—”Cupid Day”—should be one big party, a day of valentines and roses and the privileges that come with being at the top of the social pyramid. And it is…until she dies in a terrible accident that night.
However, she still wakes up the next morning. In fact, Sam lives the last day of her life seven times, until she realizes that by making even the slightest changes, she may hold more power than she ever imagined.