Afterlife of Holly Chase by Cynthia Hand

Holly Chase has the job of saving souls, but it is her own that she realizes needs examining. On Christmas Eve five years ago, Holly was visited by three ghosts who showed her how selfish and spoiled she'd become. They tried to convince her to mend her ways.

She didn't.

And then she died.

Now she's stuck working for the top-secret company Project Scrooge--as the latest Ghost of Christmas Past.

Every year, they save another miserly grouch. Every year, Holly stays frozen at seventeen while her family and friends go on living without her. So far, Holly's afterlife has been miserable.

But this year, everything is about to change