Hallmark of PC teams:Nice that SOMEONE actually brings this up. They had several chances to add points. They didn't.
A) Once you get the lead go with pure zone on defense and change up the offense, going away from what's been working.
B) If you're behind, keep doing the same thing that's not working on offense, except in the 4th quarter when you free up the QB. Stay aggressive on defense. At least until you get a lead. Then, see A).
edit: C) Adjustments are for losers. Don't do it. Stick with gameplan. Trust me. It'll work.