This answer depends somewhat on how your package looked academically last year. If you had strong SAT/ACT scores and strong grades in math, science and English in h.s., it was probably a numbers game and USNA is satisfied with your ability to handle plebe courses. In that case, your courseload may not kill you.
If, however, your record wasn't as strong as it could be academically, USNA is looking to your college performance to see if you can handle the academic load at USNA. In that case, it's important to take the plebe courses. Also, USNA will want a letter of rec from your college math prof and, if you don't take math, you won't have one. You'll need to contact your RD to see what to do -- do not assume a h.s. teacher rec will be ok.
In your situation, I would contact your BGO and your RD and explain the situation. At the end of the day, some college students can't take all of the plebe courses, and USNA recognizes that. I had a college student 5 yrs ago and the ONLY plebe course this person had taken in 2 yrs of college was Calculus, in which the candidate earned an A. That candidate was admitted, majored in math, and went on to a very successful USNA "career." Just graduated.
So, not a death knoll but needs to be managed carefully. Also, if you've not done so, contact your RD to find out what caused you not to be admitted. That is what you need to work on.
