Learn how to apply all of the major theorems. You still have maybe 20 hours, right? I am not in the US right now, so I have no idea.
Anyway, I was in your shoes my last year of Uni. I pulled a B+ in a multivariable calc class I had slacked in all semester. I ACED the final, having been totally ignorant a few days before, and not having taken a math class for 2 years.