Typically once you have the FOPE DST enabled and running updates are done in an incremental fashion.  The FOPE DST makes use of what is called a DirSync Control http://msdn.microsoft.com/en-us/library/ms677626(VS.85).aspx in order to search for incremental updates since the last LDAP query to AD.  This control uses a cookie to pass to the Domain Controller which allows to the DC to only report back changes since the last DirSync Control LDAP query.  In order to force the DST to do a full synchronization we need to be able to clear that cookie so that a full LDAP query is performed.

In order to clear the DirSync Control cookie you will need to have the DST Powershell Environment installed.  Typically this is in the same program folder as the DST in your Start Menu however if it is not their it could either indicate that Powershell is not installed on the system or that the DST was installed prior to Powershell being installed.  In either case you will either need to install Powershell and reinstall the DST or just reinstall the DST to make sure the DST Powershell environment is available if it is currently missing from your system.

Once the DST Powershell environment is avaible you will want to start that and then issue the command "Clear-SyncCookies".  FYI the DirSync cookie is actually stored service side and retrieved each time the LDAP query is performed.  When the "Clear-SyncCookies" command is issues it connects to the service and clears the DirSync Control cookie.  On the next synchronization that occurs the DST client will no longer have a DirSync control cookie to pass to a DC and this will result in a full synchronization taking place.