"RE" finishing garage floor question?

[Titan 3]

I want to refinish the floors in my garage, but could use some insight... My floors already have a finish on them, and it's in great shape. No chipping or pealing, at all. I just want to change the color/freshen up the finish. Any suggestions on prep work before refinishing? I was going to sand the floors with a 200 grit paper and lay down the new finish. Am I way off base here?

Thanks!

 

[SUPERCOAT]

I would use a much more aggressive sandpaper (40 or 60 grit) thoroughly scuff up the existing coating (and knock off anything that might be loose).

Clean it thoroughly and you're ready to go.

 

[Irondrive]

Home Depot tool rental has a floor sander and varying grit sandpaper. I always use the 36 grit when I have a nicely bonded floor to go over. I get about 100-125 sq ft per disc. They are about $6.50 per disc and the machine is approx $80 day. Works so well I bought a machine just to rough up old epoxy.