Recovering rancher server to new aws instance - re-register nodes?

I am attempting to recover a rancher server to a new aws instance. I can restore the rancher container and bring up ranher, but my kubernetes cluster wont come up. Ive updated the server-url in global settings, but I believe I need to re-register the nodes to point to the new cattle-server ip. My cluster is set up using node pools - how to I re-register - do I use the docker run command? If so, how can I get a token? running rancher 2.1.3