Calebd, ck out
SailCare ... not sure how they re-resin, but here's an overview. I'm sure the folks at Sailcare will explain further if you call, as they are very helpful.
The Sailcare treatment is not for new or practically new sails, but for those like the tread post describes. "Old, dirty, stained sails" are ideal candidates.
Spot cleaning a stain is a different story and best done at home/marina with a cleaning agent like lime, vinegar, etc.
In the DC area, I have also used Potomac Sailmakers, located right off I-95 in Alexandria, for cleaning, repairs and recutting sails. Good guys, good work.