Ok, there's some thread about GE on Flyertalk but it seems to be a year out of date and primarily for Americans.

Anyway, I dug out a scrappy bit of paper earlier with my Global Entry details etc. on it and it says it expires in Oct 2021 (well, 5 years after I first got it in Oct 2016).
Had a look at the US website, but other than a completely fresh application, I can't find anything about renewing (assuming of course you can).
Anyone know the present situation on this? No idea if I'll get into the US this year without a trip to Mexico etc., but it would be useful to have it in place should things actual open.