Would it be too late to somehow redeem myself in senior year? My GPA in junior year was still above a 4.0, but I feel that I didn’t perform at my best.
Thanks!
You give way too little information for anyone to judge. It depends on how bad your junior year was relatively to your class, and what schools you are aiming for. Just remember that nothing is impossible. 
Oops, I’m sorry about my vagueness; I didn’t do so well in my AP classes. I got a C & B in AP Physics 1 (which is extremely difficult at my school; most people get D’s & F’s), A & B in AP Lang (the B was 89%, and I’m terrified of the fact that I deproved), and B & A in AP Calculus BC. Thanks so much for your help!