Wheatley, who arrived on loan from Old Trafford until the end of the season in January, has not been involved in the last eight match day squads after initially featuring three times in League Two.
Experienced frontman Jamille Matt and MK Dons loanee Ellis Harrison have been the preferred front-two in recent weeks, although 37-year-old Albert Adomah has started the past two games.
Fellow January loanees Nathan Asiimwe, Darius Lipsiuc and Alfie Chang have also struggled for game time, with the latter pair yet to play a single minute.