I am a recently retired prof of biology/premed advisor with 40 years of experience. There is seldom a simple answer to this type of question. What you should do depends. I always believed that every student who can get accepted to college can be an A student, but of course many are not. And I believe the answer to why not is complex. You don't lack the intelligence required. Among the coomon problems are poor choices of course combination, having a job and working too many hours, boyfriend/girlfriend taking up too much time, uncertain motivation, poor study habits, partying to much, at the wrong college for them, etc. Before you can change your grades you have to have answers to these questions. Otherwise your grades will remain the same.
No professional school accepts grades lower than C and a string of Cs is not good enough.
Yes, you will have to repeat such courses, but if you can't get a handle on what is going wrong, history will repeat itself.
I always recommended students in your situation talk to a counselor in the counseling office. Most resisted, partly because they think that doing that means they are psychologically ill. Bad mistake.