If you try to liquid bleach it- it could ruin the fabric all together.
Did you add salt to the dye when you dyed the fabric? If not, you could try washing the fabric in a washing machine and hope that some dye leaves. Sometimes machine washing "unfixed" fabric can lighten it up a bit. Next time I would recommend dying a small amount of fabric first and record the times and amount of dye you used.
Also you could try sun bleaching it- lay it out in the sun for a couple of days.
The only problem is that whatever way you lighten it up you'll find it hard to match if you run out of fabric. Good Luck