Spend some extra time studying and you miight be able to increase your homework and test grades a bit, and that might keep you at a C. I was surprised how much a few minutes of studying before a test helped.
You do still have another chance though even if you do fail it, sucks to have to waste another semester, but in my experience you can often speak to somebody to get let into a class you don't have prereqs for if you are taking that prereq during the semester. I actually have a number of classes that require college algebra as a prereq completed and passed, but haven't actually passed college algebra yet. (God I hate irrelevant math)
Though still try to pass it. I failed College Algebra twice, once with an F, and once with a D that they don't consider passing. And the school has a policy where if you fail a class twice you have to pay double to re-take it, you don't want to get to that point. My Fall 2012 Math class costs more than all the other classes I have that semester combined, and I'm trying my darnedest to pay for classes myself without government aid or loans.
Study more, especially for a little bit before starting any graded assignment. Might do a bit better on the assignment if you warm up a bit first. But there are options in case you do fail that can lessen how much you get held back by it.