Oftentimes changes made to your project code are not immediately reflected in your application. When this happens, there are various cache clearing strategies you may want to employ.
For Firefox browsers, the shortcut key ctrl-shift-del will bring up the Clear History dialog box permitting you to clear your cache.
For Chrome users, this same shortcut key ctrl-shift-del will bring up the Clear Browsing Data dialog allowing you to empty your cache.
For other browsers (IE, Safari, etc), there is a fairly comprehensive and up to date wikihow site that explains appropriate steps based on the browser (and version) you may be using.
Sometimes code changes that result in updated KML will require some trial and error. At times, such changes will be reflected in your application through a simple browser refresh. At other times, these changes may require the clearing of your browser’s cache. At still other times, it may help to clear the cache on your Google Earth client application.