My current boarding school isn’t a school that makes me happy, it doesn’t suit my needs and isn’t the most rigorous academically or athletically. I’m considering giving it a chance for a year and seeing how it goes but in the occurrence that it doesn’t turn out to be a good fit for me I want to be prepared. In 8th grade I was very depressed and had no motivation so this really hurt my grades, which resulted in me not getting the best SSAT score and eventually not getting into the best boarding school. Maybe it’s because of my vanity but I am considering applying to more competitive/prestigious schools when I get my act together this year I intend to get straight A’s, kick a** in sports, and start and join clubs (that I have a genuine passion for). How will this help my admissions into top schools? I am considering applying for the ninth grade again (will this help admission?) since I am not ready to apply this year (I don’t want schools to see my horrible grades from the eighth grade) is this a good idea? Any advice or comments are appreciated. Thanks.
Good idea. Because if you do all that, you will probably start to really enjoy the school where you are now. 
And the schools you apply to will still see your 8th grade grades.