The suprelorin implant was originally designed to induce temporary infertility in male dogs but strangely also stops chickens laying for anything up to six months.
With my two implant girls it was a three month and two month respite from egg laying demands. It is therefore ideal for prolapses or other egg issues, such as peritonitis, giving your girl a rest from laying and her body a chance to recover. Most reports of it have been very good, but be aware it is unlicensed for chickens. It costs about £60.
It is an injection and easy to perform during a normal consultation. The needle is big though so be prepared! It is injected under the wing (make sure it stays in, I have heard that it can come out although this didn't happen with either of my girls). It may induce a small moult and your girl may feel a little off colour for a few days.
It takes 24-48 hours to kick in so if you are dealing with a prolapse still keep your hen isolated until you are sure she is not laying and the prolapse will stay put.
I have been so impressed with the implant that if I could afford to I would give it to all my ex-batts on rehoming so they had a few months to recover from 18 months of laying. One of my implant girls feathered up almost overnight - it is frightening to realise how much egg laying takes out of them.
A word of warning though, it is not a magic cure-all. It is best used in the early stages of a prolapse or egg peritonitis to be most effective. And also once it wears off, you may need to have another one if your hen is still having egg / prolapse issues.