Why do you want to go to an Ivy? What about that is important to you? Do you feel you would be successful in that environment? Can you afford an ivy or would you qualify for aid? There is a lot to think about when deciding where to apply than just settling for the well known names.
I would highly recommend you reach out to your guidance counselor at school and start working on a realistic list of schools. It might require you to do some research on your own and some serious thought about your goals and what is important to you. You should have one or two reach, a few targets, and some safeties. What these are will depend partly on your grades and test scores.
Honestly, unless your grades improve drastically this year (and you have a really good story as to why you weren’t achieving at your full potential) AND you knock the tests out of the park, Ivy’s might not be in your future. But that’s OK…they are not in MOST student’s future. There are plenty of great schools out there!