Why Are you doing a bleed in PS? Most printing isn't done from an image editing application, but from the layout program.
Other than that, a bleed is a bleed. If the shape you are referring to is a vector , you will need to copy and expand it. Although, if its a solid color.. I find that copying it, and giving the copy an OUTSIDE stroke width will can do the trick.
If by shape you mean an actual raster image, lets say a picture of a car that has been masked. I am afraid that need to be taking into account BEFORE creating the mask. :/ One band-aid solution, however, is to copy and scale the masked picture, maybe even ( while selected) apply a blur. This will not look perfect, but at least you wont get any "white" if the die cut jumps.