From: DeskNow Knowledge Base
http://www.desknow.com/kb/

How do I force a resync of contacts/calendar/tasks in Outlook?
http://www.desknow.com/kb/idx/17/083/article/

If for any reason you want to make sure that your Outlook has the most updated data in a contact folder,calendar or tasks folder, you can force a on way sync from the server.

To do so, in Outlook go to Tools/Options/SyncJe, select the Server and click on Edit. Then select the Folders tab.

Right click on the folder you want to refresh, and select Configure (see image below).

 

Then in the following dialog, click on 'Sync options' and select the 'One-Way, refresh server to client' setting (see image below).

 

Save your settings.

Then you can sync again. Remember that you should restore the original setting to make sure that syncronization will again work both ways.