Since moving to Southampton in January 2012, Sharp has been sent out on loan to Nottingham Forest and Reading, where he spent the last three months of 2013.
The forward last week agreed a loan move back to Doncaster until the end of the season and, with his Saints contract running out in 18 months, Sharp is unsure over his future with the Premier League side.
"I do not know, I think it's over if I'm honest, but never say never," Sharp said.
"I want to play in the Premier League so I need to come here and impress and I have a year left with them at the end of the season."
Sharp moved to St Mary's from Doncaster for £1.8million and he is eager to impress on his return and regain his confidence.
"I've been here before and it worked out really well and I got a lot of support from the fans, Sharp said.
"I feel I'm at a stage in my career where I haven't played for 12 months and I need a little lift and hopefully the fans will give me that and I will pay them back with some goals."