the only way to get updates to env-entries in a webapp in websphere is to reload the webapp - i.e. you may need to restart your application.
if you want to be able to configure environment properties after you've deployed an application, but *not* restart your app, then one good option for websphere is using the JNDI namespace. WebSphere has a whole raft of configuration options for it's cache of JNDI namespace bindings that will let you change the values of variables bound to JNDI names and get the latest settings at runtime. Cache options are on/off, entry time to live, manual refresh, etc,
Dave Clark<br />Senior WebSphere Architect<br /><a href="http://www.versant.com" target="_blank" rel="nofollow">Versant Open Access - JDO2 & EJB3</a>