// My question is more....if they hold a referendum after 7 years to leave, should there be another one 7 years later to rejoin? Or does that just depend what the result is? //
My only point is that no time limit can have any legal status. So, in short, maybe. But only if there were enough sentiment and political will to revisit the question. There might be, there might not be, but no law can stop the question from being revisited as often, or as rarely, as the People wish.
// It seems a bit like Brexit, that some people called for another, because they didn't like the previous result. Maybe there should be a standard time, on the same subject? //
Yes, I did wonder when the Brexit referendum would get mentioned. Same answer: there is no legal force against a further referendum being held, if the People wish it*. Which they didn't.
*Or, more pertinently, if Parliament wished it, as Parliament makes the laws. But then, Parliament didn't wish it either.