|Previous to ST 7.51 (e.g. ST 7, 6.5 or 3), you used the NameConvUtil.exe utility to update name changes. The new servers can do via CSV files. What the documentation doesn't also tell you very well is that it also does the LDAP conversion, too.|
Simply, create a new text file called say ldap.csv. The file should have the text LDAP in it (w/ no trailing comma needed).
You then use the standard Sametime Administrative console to have it convert the names in vpuserinfo.nsf.
BTW: If you just copied (file database new copy - don't do replica) from an old ST server, do design refresh on it.