You need to clear the Java Web Start applications folder. Exactly how to do this depends on which version you are using, but here is the general idea:
1. Start the Java Web Start Application Manager. It might be in a "Java Web Start" program group in the start menu. Otherwise look for javaws.exe under the JRE path.
2. Go to the Preferences section. On mine its available from the menu under File->Preferences.
3. Go to the Advanced tab. There should be a section labeled Applications Folder Options with a button labeled Clear Folder. Press this to delete the cached applications.
Next time you access the tools, they will be downloaded again.