How to Safely Update a Document's Styles from its Template Without Using the Organizer

If you want to update the style definitions of a document with the style definitions in its attached template, you can manually select Tools + Templates and Add-ins, check the box which says 'Automatically update document styles', click OK; and then, because that setting is sticky (and most of the time, undesirable), immediately select Tools + Templates and Add-ins again, deselect the 'Automatically update document styles' box, and click OK.

Rado, Dave, Margaret Aldis, Ian Sharpe and Beth Melton. Word MVP Site, The (2002). Articles>Word Processing>Style Sheets>Microsoft Word