I don't think anything removed is coming back.
When someone's arm is cut off, the body's like "Job's done" on the healing end once the bleeding is stopped and the skin has formed over what's left of what once was a limb.
Becoming a werewolf isn't going to make the body suddenly go "Gee, lets fix that better".
Though, I can see things like piercings closing up (they do that anyways).
And since a lycanthrope usually possesses a sheath (if for nothing else, to keep certain things from flopping around when you move and like, totally ruining your scary-ness..
) I could see the foreskin possibly returning simply because the sheath and foreskin are pretty much he same thing and there's no reason for the body to remove it after the shift and there's no way for it to know it shouldn't be there because it was previously removed.
Of course, there's no way for lycanthropy to know how short or long your hair was, yet lycanthropes generally retain their hair-length. So its' debatable that the foreskin would return.
I'm not a fan of the super-regenerating werewolf, myself. There is some regeneration, but its more in the terms of healing damagequicker and easier.
Lycanthropy isn't going to fix your eyes, or give you back a lost limb.