I have recently kicked up a new node with new Pub ID

Unfortunately right now we don't support multi node per user, but it's in the works. For now, you will have to start with the new node as if you had a new account. Once we have the feature you will be able to merge the two accounts.

Is there a way to replace my old one with the new one? I only have one node

No, because all your swaps would be strangely reporting to have failed, etc. Sorry! Bear with me.