Is there a plugin that continually updates code?

As an eight year user of IDEA, I love it to bits of course, and take for granted its code completion actions.

I have need of a plugin that once actioned will continually update a particular block.  It would watch for changes to particular method signatures, and rewrite code elsewhere in a source file accordingly.

Most code-completion plugins, or light-bulb driven invocations of plugins from the editor are once-off actions.  Are there any that will continually work that I can be inspired by ?

- Paul