My son’s school shirt which is navy blue has a very small patch where some residual bleach in the washing machine has removed the color. Are there any products which allow a partial re-dyeing or touch up? any other advice? thanks Jane

Jane,
I am sorry, he will have to wear it like that or else get a new one. Household chlorine bleach cannot be over dyed. A dye house in Canada, www.dyeproservices.com, has a service of restoring bleach damage by removing all color and then over dyeing it. Check it out if you want to see how much it would be.
best,
Jennifer