Remove the Identity Server from the Identity Server cluster configuration. (See Section 6.1.3, Removing a Server from a Configuration.)
Delete the Identity Server from the Administration Console. (See Section 5.1, Managing an Identity Server.)
This might not be necessary, if you used a new machine for the restoring the configuration.
Assign the new server to the Identity Server cluster configuration. (See Section 6.1.2, Assigning an Identity Server to a Cluster Configuration.)