Can you submit an abstract that was accepted to a conference but not presented, for a different conference? Our group has submitted an abstract to a conference for an oral presentation (not the proceeding track), and it was accepted. We're scheduled for an oral presentation, but it seems like we cannot make it to the conference because of travel expenses.

I was wondering if we withdraw our presentation, can we submit the same abstract to a different conference? In particular, we're considering submitting it to the next conference of the same organization; would there be any upside or downside to that?

( I read this question, but this is about whether the abstract is considered published or unpublished and does not discuss whether it can be submitted for a different conference or not.)
In my field, and I think in other traditional disciplines as well, is pretty common to present talks or posters more than once.
Thus, your doubt has no ground. Presentations aren't papers, they are dedicated to an actual audience, so you could resubmit the "basically the same" work even attending this conference you cannot in fact attend.

(How many times it makes sense to present the same core depends on many factors I am not going to list here) . 

I recommend you to explain to the current organizing committee, or the branch in charge of the scientific content of the event, about your impossibility and why. Let them know you will try to submit and attend the next conference.

Also, in case the current accepted abstracts go printed, try to reformulate it at least a bit. This has nothing to do with copyright or self-plagiarism but it something I always do not to convey the idea of laziness or that I and my coworkers are prone to sloppy copy and paste.