By how much can I raise my GPA in my final year of highschool?

The theoretical maximum GPA you can have is a 2.714 Unweighted and a 3.714 Weighted.

All the other answers are incorrect because you only have 1 semester of grading to improve your GPA prior to applying to colleges not 2. You will have applied and have received your college decision prior to your last semester of grades being recorded.

Hope that answers your question.

I would say to actually take less honors classes. From what you're mentioning, it seems that taking too many honors classes has led to a decrease in GPA. I think you should take a step back, take some study halls so you can get your unweighted in the best order, and also have less stress as well.

If you only have one year of high school left, there is not much you can do regarding your GPA. If you were to get a 3.9-4 this year, your final GPA would end up being short of a 2.9. As for weighted GPA, I cannot say since I don't know your school's grading policies, but taking and succeeding in honors or AP classes is the most sure way to bring it up.