Question, is it okay to desolder a cap and then try again for a better joint on the same cap? Or should I just try again with a new cap?
in general, desoldering is more difficult than soldering ... if you have spare components on hand, it's usually easier, to replace a component than it is to re-solder the same part ... when you're working with a fresh component, you're not worrying about any possible heat damage ...
OTOH, capacitors can take a lot of heat from the soldering process without damage ...