If it is just one class you are having trouble with, you will most likely be given a second chance. Now, if you are in the square root club, things may be different.
Seek help. You can ask your instructor or ANY instructor for EI. I know my main instructor didn't teach in a way I always understood well, but one of the other teachers made things make sense very easily. You also have other cadets who will help you, both your classmates and upper class. I forgot what the other office is called, but there is something like a Student Learning Center with staff that will likely help, as well.
If you study hard, and get EI early and often, it is likely you will pass. Even if you don't, the faculty is much more willing to give second chances to cadets who show that they are willing to work hard.