I’d done this some time ago via console.

My RE partition had sat before my main partition - and since you can’t shrink partitions at their start (left) with fdisk and I didn’t want to boot up a Linux pen drive, I just shrank the main partition at its end (right) and moved my RE partition to the now freed space at the end.

I’ve made the old RE partition available, but since it’s just a few hundred MB, I doubt I’ll ever actually use it. :-P

PS: If you do it via fdisk, just make sure you first enable the new RE before disabling the old RE. Otherwise there’s nothing that can be copied to the new RE - I’ve made that mistake and had to get the missing files from a Windows ISO.