Microsoft has released a nice free utility named “Active Directory Replication Status Tool”.  This tool can be used to manually check the replication status on your domain controllers.  When you click the Refresh Replication Status button the tool performs a discovery of all domain controllers in the forest and then collects detailed replication status information for every Active Directory naming context.  The tool can be downloaded from the following link:

Active Directory Replication Status Tool

AD_REPL_STATUS