After application clients are downloaded, they remain on the client until they are manually removed. Use the Java Web Start control panel to discard downloaded application clients that used Java Web Start.
If you undeploy an application client, you can no longer use Java Web Start, or any other mechanism, to download that application client because it might be in an inconsistent state. If you try to launch an application client that was previously downloaded (even though the server side of the application client is no longer present), the results are unpredictable unless the application client has been written to tolerate such situations.
You can write your application client so that it detects failures in contacting server-side components, but continues running. In this case, Java Web Start can run an undeployed application client while the client is cached locally. For example, your application client can be written to detect and then recover from javax.naming.NamingException when locating a resource, or from java.rmi.RemoteException when referring to a previously-located resource that becomes inaccessible.