Carbona makes a color run remover, selling at my local Hancock fabric store. Worth a try. The Retayne may have already set the runs, though. Just how bad is it, and what colors are involved? Fabric paints, markers or cray-pas may be a solution. Can you post a photo?
Also, what kind of dye did you use? Some natural dyes are never going to be colorfast if not properly set at the time you dyed them. When dyeing anything, it is important you rinse the fabric until the water runs clear.