Right-click the existing Web Client site, and click Tools > Update Web Client Site.
If you see an access denied message, cancel the update, and check that the application pools have been stopped in IIS.
When a Web Client site is updated, the existing Stamps and Symbols folders will not be be overwritten. For example, \WebClient_Sites\[Site]\viewers\resources\symbols\ and \WebClient_Sites\[Site]\viewers\resources\stamps\ will not be overwritten with any content from the installation folder, such as \SDx\SDxClient\viewers\resources\. Also, any existing .ttf or slug font files, folders, or other files in the fonts directory folders will not be overwritten if the content does not exist in the installation folder.