Hi Eric,
I was a NMMI prep last year and I am currently a USMMA Plebe. There are a couple of things to take into consideration with your question here. First, you want to stay away from D's and F's as much as possible. Second, if you failed a class last semester and you are re-taking it for the second time this semester and still having trouble with it, you are going to want to try to get that turned around ASAP. Re-taking a class in itself wont get you thrown out, but if you aren't improving in it the second time around, it wont look too good. The biggest thing to keep in mind is that the academy wants to see that you are improving/advancing academically while at NMMI. To answer your question in short....yes it is POSSIBLE to get in, but there are several different criteria that KP will use in order to evaluate your file.
Now for my advice to you....keep your head in the game, you have half a semester left to make the best of your NMMI grade and show KP just what kind of student they will have on their hands. Use your NSH time wisely, study with the smartest kids in your class and if you have off periods, meet with your teachers as much as you can, this will show them that you are serious about making it to KP. Believe me, I was horrible in math when I first came to NMMI, but I made it work by setting up appointments with my teachers to work on problems, burning the midnight oil, staying on campus while friends went out on the town or up to Ruidoso and getting off facebook/youtube/netflix (yea it takes up more of your time than you think...), etc.......Bottom line is that I made my NMMI calc work grade wise with some very low C's and I am convinced that if they didn't send me to NMMI that I would already be out of KP for my math grades.
Remember, as a sponsored prep, you have a golden ticket into here, your only "job" is to make those grades happen...Focus on your potential, not the minimum of what the academy will accept.
Best of luck!