Hey!
This is just my hot take on the situation, but I think that if you've gotten to the interview stage, they're definitely taking you seriously as a candidate, and as they already know your scores/stats, those scores/stats are probably not a prohibitive factor to your getting admitted. After all, the whole point of sending out interview invitations
after you've received and reviewed applications is that you should have winnowed down the field of applicants to the ones you're more interested in (as it would be too costly and time-consuming to interview every applicant ever). So basically, you're probably okay on retaking the test for now.
That said, if you end up getting
waitlisted (and I should say that I don't know that this is particularly common for deferred admission programs), then it would probably be a good idea to retake the exam, as anything that might bump up your admissibility helps. But if you don't get in and you were planning on taking the GRE closer to matriculation anyway, just hold to that plan, take the GRE in ~2 years, and apply to schools with that score (which will also double as your scholarship-consideration score, as you note).
I'm sure some actual admissions people will have more informed things to say about this, but I figured I'd weigh in in case it helped.