From the Maintenance tool you need to create a new connection to the database you have restored.
Set the connection string to point to the new DB and connect.
Once it is connected, you will notice the connection string has changes and showing the old settings as they were configured in the old server.
Still in the maintenance tool, select the "Schema Repository" menu -> Upgrade -> selected connection (or other if the connection profile you want to change is not selected).
You will then be able to change the connection settings to point to the new server and DB and it will be set this time.
Once this is completed, you will need to use the ClearQuest Designer tool and to run an update to the User databases.