You should not use Retayne once a fabric is in a quilt and bleeding. It could permanently set the bleed. Retayne should only be used on fabric yardage, although you could use it on multiple fabrics of similar color.
PaperPrincess is right. Wait until the quilt is finished, then wash with Synthrapol *using lots of water*. Domestic front-loaders do not use enough water to dilute dye bleeds. You can use a domestic top-loader if you can use enough water to dilute any dye bleeds. If the top-loader has a central agitator, you need to turn off the machine and hand-agitate as central agitators are hard on quilts. I take my quilts to a laundromat and use a large front-loader, and I routinely use Synthrapol in that first wash just in case there are any dye bleeds. Synthrapol suspends loose dye particles in the water so they are rinsed away and don't have a chance to settle into other fabrics.
If you Google, you will find that many people have done tests that show Dawn is as effective as Synthrapol. Just be careful, whichever one you use, to not use too much. Both can create a lot of suds (which, incidentally, will void the warrant on a domestic HE front-loader).