Sandisw answered it, I just wanted to give you some extra backing that they are 100% right. Sandisw helped me with a similar question about a week ago. We were looking to, sadly, cancel our February trip but have our much longer/more point expensive November trip. Our UY is September and the Feb trip was 2021 points. I was able to cancel the Feb trip, got 150 2021 points back, then modified my 2022 November trip, didn't change anything just went to the end, and it showed I had 150 points I could bank to 2022 to cover the trip. I did it and my 2021 balance is 0, and I now have 150 2022 points that were freed up by me using my 150 2021 points.
For all the usually deserved flack Disney IT gets, I was surprised how easy it was to make that happen.