1. Browser checks if appcache have been modified on page load. Usually if you have changed only some content in existing files, browser will not detect that cache needs to be reloaded.
2. If you want force updating, use update method of application cache.
window.applicationCache.update()
Important: The update() method only updates the cache—not the web application or anything that is loaded. The easiest way to update the page when the cache is ready is by reloading it:
location.reload();