Steve Evans wants to hold on to striker Tyrone Barnett, who has already scored six goals this season, including a double against Bradford.
The summer signing from Macclesfield has already attracted interest from elsewhere.
Evans told the club's official website: "Tyrone has responded to the work we are doing with him on the training ground and has shown a vast improvement since we signed him in July.
"Then he was a good player with potential, now he is a very good player with even more potential.
"As a club, we could have sold him on the latest transfer deadline day last month for what was a significant six-figure sum with a number of further incentives, but my directors said no and I was delighted.
"He is a big part of what we are trying to achieve this season. Getting into the top seven come next May will not be easy and for that to happen we will need to keep players of his quality in the camp."