Manged to dent the hell out my 2 week old rear rim at BPW last weekend, there’s a bit of a buckle and a dent – I think the rim is dead.

Superstar are offering to rebuild it for £40 under their crash replacement policy, but it takes a week and they’re my only wheels – how many kittens will die if I fit a new rim to the exisiting spokes?

I’d do it, particularly as you’re just swapping the rim and the wheel is not very old – unless any of the spokes are obviously damaged. TBH a one off overload probably won’t be likely to do much harm and may actually increase the fatigue life of a spoke. Worst case, some spokes break and you replace them later.

it’ll be fine if they are no too bent or kinked from the crash

So long as there’s no damage to the spokes then yeh, re-use them. Easiest way is slacken off all the spokes first, (don’t undo them from nipples altogether), then tape the new rim to the old so valve hole lines up and then just transfer nipples & spokes over one by one.

I’ve taken wheels apart because the rim was toast, I keep the old spokes for spares if I have any breakages.
No issues with reusing 2 week old spokes.

I have some road wheels with 40-year-old spokes – crack-on!