It varies by manufacturer. Several offer a "full rebuild" for ~ 50% of MSRP, whereby you receive (after several weeks) a brand new cartridge in the old body. E.g. Koetsu, Ortofon. I like this option, but manufacturers dependent on a single ageing master (like Koetsu) mean it cannot be counted on for the long run (the Koetsu master passed away last year - RIP Fumihiko). I used the Koetsu option a few times; they really are good as new. Note MSRP can be relative to the distributor network you send it into! Ortofon handles these cases direct, which is much better IMO. If you can afford $12K one time, you can afford a $6K refresh every few years (don't use it for background music lol).
Some offer only "trade in" value to a new cartridge which is often paltry (e.g. 25%). I do not like these options. Benz Micro offered generous trade in allowances in the 2000s, but took those away when they couldn’t keep up with demand.
And then you always have the 3rd party retip / rebuild option. Retip is only possible when the coils, cantilever, and suspension are still intact. Both options here usually cost FAR less than the above options. None of the cartridge manufacturers make their own styli (and very few their own cantilevers), so it is often possible to retain much of the original design intention this way.