When we were on vacation once, the cat sitter locked our kitty out of her litter area. Came home to an awful pee problem and the carpet was new!! I used the information at this site and it is now completely gone!!! It did take several applications, but that was for carpet and padding. I don't know what the 3% peroxide would do. Do you have a scrap of the fabric left to test on? If it discolors the fabric, try just the vinegar and baking soda steps. Good luck. Cat pee is truly difficult to remove, but this worked for us.
http://www.catsofaustralia.com/urine...al.htm#Recipe0