Just to be sure:
1. You have a VBR server, and an additional server which is your repository. You added this by IP-address and not by hostname. Is that correct?
2. You will change the IP of that repository server to another subnet (and I assume the networking part is all ready)
If this is the case:
Personally I have never done this type of operation but: One of the great things about B&R is that you won't need to recopy. If you are going to re-ip it, then chances are big that you will need to re-add it to the infrastructure and do a rescan. Most probably you will need to change the jobs also to point to the "new" repository (so that they continue to use the correct chain. See here for more information: https://www.veeam.com/kb1729