Just because your agency has been around for a long time doesn't mean it needs to act its age.
In fact, one your greatest strengths/advantages would be to sprinkle in a little immaturity when making a few key decisions.
It's the constant rationalization against "the way it's always been done" that prevents real progress from happening.
If you can move faster than everyone else they'll still be planning the thing you stopped doing six months ago.
That's what I talk to Bogus Handzel, of Handzel and Associates, about as he continues to push his agency forward without starting over.