Lc should be regenerating the FormGuide when it detects a change in the template's timestamp, or when the timestamps of any related collateral become newer than that of the form itself. Any FormGuide change must be applied, and then the form must be saved via the WorkBench Designer's save button.
Also, you can login into Lc adminui and navigate to the Forms admin page where you can manually clear the current forms cache.
This implies that for IE, the configuration setting for temporary (cache files) may not be correct. I believe it should be "automatic" or "every time you visit the web page".