Honestly... I've spoken to an adcom about re-taking courses...
Personally, there isn't much to LEARN really from re-taking an undergraduate course in this one adcoms opinion. Retaking a course isn't going to show anyone anything. Now... taking a harder, upper level course will demonstrate that you have the capacity to succeed.
Big deal, you got a few C's in organic chemistry. Not the end of the world. It used to be. But not anymore. Just like people couldn't take the MCAT more than 3 times in their lifetime. That's gone.
Little secret, if you take the MCAT more than 3 times, and show improvement.... the LAST/BEST score is what most schools care about. Although some schools are trending towards averaging.
Now back to organic..
The reason you got the Cs... if you figure that out, you're good to go. Learn from your mistakes, brush yourself off and keep getting on the horse. School is a game, sometimes you gotta get hit in the face before you muscle up and learn how to play.
Also, it could be that you're just not organically inclined. This is NOT a problem. Ask any MD/DO that is not in research exactly how much organic chemistry mechanisms they use in day to day practice. Organic is nitty gritty memorization that really has no relevance. Not like cool stuff like physiology or anatomy that you can actually conceptualize.
If organic wasn't a requirement of bio majors and most medical schools... instead of 500 people taking it.. there'd be 50 people taking it. (Comes from an organic prof at my university).
Best of luck. Move on and upward!