Using Eclipse 3.7.2 or 4.3.1, I ran into a problem where I wanted to change the name of the perspective in an RCP application. I changed the title in the bundle.properties file and relaunched my application from within the Eclipse IDE. The title had not changed. My immediate thought was that the title was cached in the application workspace data. So I relaunched the application after changing the launch configuration to clear that data first. The old label remained. I cleaned and rebuilt the application projects. I exited and re-entered Eclipse. I shook my fist in frustration. None of these would make the label change.
A scan of all files within the IDE .metadata directly yielded a couple of binary files that contained the old string. After some head-scratching, it was determined that these files were in the application's configuration area. This can be cleared in the launch configuration by switching to the Configuration tab and ticking the Clear the configuration area before launching checkbox. After that, the new label took effect.