Anything with a red dye in it has a chance to stain your clothes so nomatter what method you use it is probably going to stain.
I’ve found that the bottles of fake blood you can purchase often wash out of clothing. Otherwise, bleach may get the colour out if the dress is entirely white but that isn’t a guarantee.
If you just want a blood effect maybe you could creatively make use of these ?
(c) Cosplay Tutorial – Read entire story here.