First off I would assume you made all the correct changes to the CRS server:
1. Updated Directory and Repository Configuration
2. Updated JTAPI Provider IP's
If you have done that and ALL your CRS Engine subsystems are "In Service" you then need to go to each of the agents machines, and go to the registry:
HKEY_LOCAL_MACHINE\SOFTWARE\Spanlink\Site Setup and change the DWORD's LDAP_HOSTA=, LDAP_HOSTB=