Imported cluster joining new Rancher server

Hi, I am a newbie on rancher and k8s.
I’ve just built a new rancher server and imported a k8s cluster.
However, the rancher server crashed when I was testing backup / recovery.
Then, I installed a new rancher server, and try to import the same k8s cluster, what should I do with my k8s cluster still belongs to the crashed rancher?

I tried to import the cluster on rancher and paste the command on my k8s cluster “curl --insecure -sfL xxxx.yaml | kubectl apply -f -”, it shows: / proxy-clusterrole-kubeapiserver unchanged / proxy-role-binding-kubernetes-master unchanged

Then the portal shows “pending” all the time.
I wouldn’t find any hints on rancher doc about leaving rancher by command. Please help.