Generally the changes I make show up within the project automatically or just on a quick save of the project.
Occasionally I have had to quit rapidweaver and restart for changes to appear but personally I haven’t attributed this to Rapidcart, and it doesn’t seem to be the norm.
With a bit more experience with RapidWeaver, I’ve noticed that to see (many or most) changes reflected in Preview, including those made independent of RapidCart, I need to save, quit, and reopen. At least I know who to blame…