If you already needed to change the vCenter IP address, by default you will have issues when connecting to it using Web Client or the conventional client- it is not possible for the vCenter service to connect to the SSO server,if they are installed on the same server. The problem resides on the fact that the SSO IP address is stored inside the SSO database. The KB http://kb.vmware.com/kb/2033516 is not exactly regarding this, but helped me to resolve the issue in an envirnoment I am configuring. In my case, with SSO in an SQL Express local instance in the same machine as vCenter, I needed to do:
sso_server_folder\utils> ssocli configure-riat -a configure-db --database-host localhost -m master_password
master_password is the admin@system-domain password. With this, I could resolve the problem, just restarted SSO and everything was up and running again.