Spray OxiClean on them. It will get the stain out.
True story: I had a serious leg injury a couple years back, and I didn't have an ice bag or any frozen peas to keep down the swelling. I used a frozen bag of blueberries on my leg, and then fell asleep on the couch. It was all I had in the freezer at the time. Woke up a couple hours later and found that the blueberries had melted and the bag leaked and the entire end section of my couch was stained purple!! Put some Oxi Clean in a spraybottle with water and sprayed over the stain. It vanished completely. Stupid thing for me to do, but I was kinda doped up on Percocet painkillers.