I had a BigCo manager once who gave me some really good advice, that is to publicly let it be known that you are interviewing at least once a year. Now, in your case I'm not sure I'd let it generally be known how much I was interviewing, but letting people know you're looking at what's out there is usually not too bad an idea. Who knows, maybe they'll be able to do something to address your concerns?

But if not, and you just don't have any passion there, please leave. Life's too short to work on boring crap and decent developers are rarely at risk of starving.