May have to reapply-advice needed

Okay, so if my GPAs are low and my MCAT need works but I’ve graduated how would I go about improving? I think my job pays for up to 6 credits so I could take science classes while studying to retake the MCAT next year. My GPA is lousy (3.3C, 3.1S) and my MCAT sucks (500) so how long should I work on my app? In addition, I have many Ws due to now resolved medical issues so I know my app is subpar.
Source: Student Doctor Network - Category: Universities & Medical Training Authors: Source Type: forums