If you use a caching plugin, you may have an option to include custom PHP code when flushing the cache manually — for example, Comet Cache has an “Evaluate Custom PHP Code when Clearing the Cache?” option where you can enter additional PHP code to execute when clearing the cache manually. Adding the following code will also clear the WPSSO object cache when clearing the webpage cache:
if ( function_exists( 'wpsso_clear_all_cache' ) )
echo 'Cleared '.wpsso_clear_all_cache().
' files and objects from the WPSSO cache.<br/>';