The midfielder initially joined on loan from Reading in September with Brian Howard going the other way; he made his debut in a 1-0 win at Derby County and completed a full transfer until the end of the season in February.
In total he has made 31 (+3) appearances and found the net four times but he has cause for concern after not being offered a new contract and could leave Bramall Lane in the summer.
"My contract is up at the end of the season so who knows what's going to happen," Harper told The Sheffield Star ."The club has not spoken to me and I have not spoken to the club so I don't know what's going on.
"I will see what offers come in and I will leave it to my agent.
"I know I am a good player and I believe in my ability. I know there will be someone who will want me so I've got no worries about that.
"I know I am good enough and I'm on a free transfer as well so no club has got to pay any money for me."
Harper insists that he has not ruled out the prospect of making a return to the Premier League.
"Every player wants to play as high as they can," he said.
"I was in the Premier League for two years at Reading so it would be nice to have another crack at it."