Can i not re-take Algebra 2 next year?

I failed it last semester. I got a B in algebra 2 first semester.My counselor said if i re-take it, I have to re-take the whole year so yeah. I will be a senior next year in high school. What happens if i dont re take it? I want to go to Illinois State University and i got an above 3 GPA (i think 3.4) and a 22 on my ACT. If I dont re take it, i would take an easier math class. I cant imagine re-taking it my senior year cause i will probably fail it even worse since ill get senioritis. lol This is the first class ive ever failed by far, I usually get A's and B's and one C always. I just messed up and got to far behind. So what do ya think?