The 17-year-old, who made 10 first-team appearances last season, is expected to play a main role in John Sheridan's side in the new campaign.
"I've got a lot of time for him. From what I've seen of him in training, he's got some really good qualities in his game," Sheridan told the club's official website.
"He's made that little step up, he trains with the first team and, even in training, he needs to score more goals.
"This year will do him the world of good and, with a good pre-season in him, next year, he'll be pushing for a place."
Harvey has been with the club since 2004.