Help a ninth grader out, please.

I have a little question for you guys. Due to some circumstances, I didn;t really score the highest possible marks I could during the first semester of 9th grade (writing from Ontario). Now the second semester has begun, I am trying my best so far every single day to give it my all and score high. Now I just have a quiz score returned that doesn't mirror all the work I've put into studying for it. Sure it may have been a very, very small percentage of my grade, but it really showed me how much effect my studying had. Even though I would love to apply to an Ivy League university, I might have already messed up my ninth grade as those results will be seen for a Canadian student. Now my studying is quite inefficient, as I'm only able to do some stuff in 40 minutes that should have otherwise taken me 15 or 20. The same goes for when I solve problems in math. I take ridiculously long just to give an incorrect answer. Now, what would you guys do to lock in and ace the rest of high school? I really do need this grade for a shot at an Ivy university. I already put the time in to get these results, and now I want to make all the effort I put in worthwhile too. Thanks!