I turned down USMA last year. I know attend a reputable college and should have between a 3.3-4.0 by the end of this year. I believe I may attempt to reapply in order to gain admittance to be a plebe. Will USMA hold it against me that I turned them down, and if so are my stats good enough to get back in?
GPA: 3.5 (it went from 3.0 to a 3.9)
Good extracurricular with three leadership positions
In my opinion it will not hurt if admissions believes that you are now truly committed to a military career. Admissions decisions are largely objective - if your WCS score is high enough, you will get an appointment (assuming you have a nomination). However, if admissions questions your commitment, you could be at a disadvantage when appointments get down to Additional Appointees, which need not be based on order of merit.
On the surface your stats look good. How they translate into WCS points will depend on the courses and how USMA weights your specific extracurricular activities. Good grades in English Composition and STEM Math/Science will help. Non-STEM Math/Science will carry less weight.
Participating in ROTC could help alleviate any doubts admissions may have about your commitment after turning down an appointment, especially with a solid reference from an ROTC instructor.
Incorporating your reasons for reapplying after turning down an appointment in the essays and also discussing them with your RC could also help. Your RC will really be the one to judge your resolve.