The 19-year-old, who has recently recovered from a lengthy struggle with injuries, aims to cement his place in Warren Joyce's reserve team this season after Weir left for Hull City and Pereira joined Granada on loan.
Mitchell scored a goal in United reserve side's victory over Leicester City last month and is now eager to come a key academy player in 2016/17.
"Personally, I feel I play best on the wing," Mitchell told MUTV.
"Preferably the right wing as I like to cut in, dribble and shoot. But I even came on at left-back recently and felt comfortable there.
"A few players in my position have left, like James Weir and Andreas Pereira (on loan), so I think it's a chance for me to get in the reserves team, cement a place, try to progress this season and help the side.
"I hope to get a few goals and the team can kick on because we're lacking a few attacking options."