Try soaking it in a bucket (tub) of heavily salted water. Then wash normally. Years ago we used to do this with blue jeans. Back then they heavily used dyes because dark, dark blue jeans were what everyone wore. I did this with all me brother's jeans and it always worked. I had a friend that used to do the same thing with jeans by using vinegar in the water. I never tried that because I really dislike the smell of vinegar. If the alternative is throwing it out, you might give it a try.