Is it possible to add further layers of prepreg to a cured part and re-bag & bake?

Will the resins bond ok to the cured parts - I'm assuming the cured part will need keying up?

Thanks in advance

X-Preg isn't resin rich, it still only has a 42% resin content which is pretty standard for pre-pregs. If you're only adding a layer or two, I would still recommend using a layer of adhesive film to get a good bond to the surface.