Skolars were heavy losers last week, falling 66-6 at home to Gateshead Thunder.
Mbu said: “We need a massive response. All we can do is put it behind us and just respond, and see how the lads come back.
“There were a lot of missed tackles and we didn’t stick defensively when we went up for one-on-one contests, and that was our downfall.
“On Tuesday we turned up at training and said ‘we’ve got eight games left and there’s plenty of opportunity for us to produce some performances in those games’.
“We need to have a positive outlook on what’s ahead. We’re only just over halfway through and we need to keep our heads and spirits up. It’s a big mental test for everyone involved.”
Mbu has no new injury problems, while York coach Gary Thornton wants his side to continue to control their destiny.
Thornton said: “We’re not looking for anybody to give us a lift up. If we win our last seven games we will finish top of the pile.”