In university it's very common to strugle with some subjects, we all have our strengths and weaknesses academically talking of course, we have son courses tha we learn easier than others and tha is completly normal, but sometimes even if we put all our efforts and try to learn the best way the subject we maybe have other things in our mind that do not let us learn in the best way, maybe personal, economic or health problems, so we are in our best shape at the moment. When we see that even if we study a lot and do our best our test or quices have not the best grades whe need to think the options we have so "safe" the course, of course if in you university they have the option of mentoring spaces with students of higher semesters, or also a space where you can ask you professors to solve doubts you should take that chance, also making study groups it's a great option, talking with your course partners about the problems you are trying to solve or doubts you have migh enlighten you and understand tha things better. If even trying all this you can't improve your grades you should take a space to make a little reflexion and be sincere with yourself, sometimes we have a lot of weight in our shoulders and can have the mind as clear as we want it, to learn fast and do ours studies as a race in a straight path, competing and comparing ourselfs with our peers, but learning it's not a race, and we do not have to compare to other, also the path we follow never it's gona be straight, it is full of hills, rivers, canyons and valleys, just as life, it's not plain, it has obstacles and we are humans that try to be better each day and put efforts in do our best so having issues learning it's normal.
Now that we know that keep in mind that if you need to drop the subject and retake it , it's okay, now that you have a more knowledge when you retake it you can clarify all you doubts, even you can have a better teacher or you have the patience and the necesary tools to learn it better.Some wise being someday said "some battles are lost but wars are won..."so retreating it's not a coward decision, you are looking for what is best for you and also taking into account that you want to keep a good average grade. Concentrate on the subjects in which you can do well and understand better, where you know that you can achieve it a little easier or with a greater chance of having good grades.
Not saying more, remember it's you decision and only yours, just take you time to figure what it is better for you and take it easy, if you love and like what you are studying it will be more simple :).
İ love this quote so much, "some battles are lost but wars are won." I had retaken a lot but I took my time to understand what I need and what I want from school/ knowledge.