I hated econ.
I would say that you should take the final. If it's the same professor (or if it's taught so that all instructors use the same material and exams), then you know what to expect next time. Also, it shows that you tried hard, and professors like that.

*And yes, I've been there. I failed calc II the first time I took it. I needed a 99% on the final to get a D... The second time I finished the class with only a couple percentage points shy of an A.