How does one's foreskin grow back, and what does one do when it does? Is there anything one can do to prevent it from growing back in the future?
1 Answer
It sometimes happen by children who were circumcised for medical reasons that too much skin is left over so they need a circumcision revision.
Such a thing almost never happens by milah. Let alone one done on an adult convert. If it does happen then the person may need a new circumcision (for maaris ayin purposes. See Shulchan Aruch YD 264:6). However it is not something rushed into. No responsible Mohel is going to do it without the person consulting and getting clearance from a urologist. Nor will he do without the presence and oversight of a competent medical professional at the time.
The only case I know of an adult who had a regrown foreskin the consensus was that another circumcision would be too dangerous so it was not done (as told to me by the two mohelim involved in the story)