I originally paid for the unlimited meal plan on UPAY but after the payment went through, I changed to the Basic DC meal plan and so my balance went from 0$ to CR 262.50$ or -262.50$. Will this balance carry over to next semester so that I can pay 262.50$ less next semester or will it go back to 0$ after this semester?
Yes, it will carry over to spring semester. Similarly, if you owe money at the end of the semester, you will be billed in December.