Before the update begins, Dreamweaver adds a backed-up version of your previous Spry assets to your site. The back-up directory is in the same location as the SpryAssets folder (normally the root directory), and is called SpryAssets_backup_currentDate_uniqueID.
The update occurs on your local site only, and updates the selected items with the installed version of Spry. Don’t forget to upload the updated Spry CSS and JavaScript files in the SpryAssets folder to your website.