I was just testing a Java Applet on Firefox and noticed that either I had to reload the page a thousand times or restart the browser, obviously this results in wasting a big amount of precious time but fortunately there is an easy way to clear your browser's JRE cache:
1. Open the Java console -> Tools -> Web Developer -> Tools -> Java Console
2. Click on "x" to clear the classloader cache and you will get the following message:
"Clear classloader cache ... completed."