Fix tie dye shirt?

[Coll0610]

I made my first Mickey tie dye shirts. I made one for me, DS and DH as a surprise for DH for Father's Day. Mine came out pretty good, DS's isn't bad but half the Mickey head on DH's is missing. Somehow the dye just didn't get to part of it. Has anyone tried re-dying a shirt to fix the Mickey? I have plenty of white around it so I was wondering if I could just re-sew the Mickey head, put the rubber bands around it and then just dye that part. I have a little dye left but none of the soda ash. Do you think it would work?