Is it too late to transfer from IB curriculum to AP classes (traditional United States public school) at 11th grade? Should I repeat my 11th Grade as an AP student?

When you transfer from IB to AP, you will most likely have to redo 11th grade, as credits usually only transfer to colleges, and not within courses in school. However, it is never too late to transfer, if you feel like your performance would be better in AP, then I would recommend transferring as soon as possible.