If you change something in your Web Service API–even a change which should be invisible to clients, like removing an API call nobody is using–you need to regenerate the client code from the changed WSDL. Even if the actual logic is identical before and after, you still need to download the WSDL, regenerate Java stubs with wsimport, and recompile.
B. Grosof, and T. Poon. WWW '03: Proceedings of the 12th international conference on World Wide Web, page 340--349. New York, NY, USA, ACM Press, (2003)