Step down and endorse someone more radical.
Piss off one of your dukes so badly that they secede.
Attack Minas Ithil. They are a juicy target and don't have any real friends left.
Attack BoM. They are half your size.
Attack Darka. They took one of your cities. (Which will probably convince at least one of your dukes to secede, because, let's face it, Eston is still Darka's battered girlfriend.)
There are lots of ways for Eston to "shake things up". All of them involve putting your current position of power and influence at massive, suicidal risk.
So let's be honest with ourselves here. We're not refusing to shake things up because we can't. We don't do it because we don't want to. I say "we" because this applies to me as well.
At least CE still gets to fight battles. 
I believe you realize that all of you suggestions are for CE benefit….
Trying to win the war from the rear again?
The Northern alliance may be shaken-up, but I believe it is too early for the crows to move in.
And after Eston cruses its allies, who will help it stand against the CE? Or will CE welcome it in its alliance?
You want to stir and shake things up? Declare war on Tara, or even Coria or Talerioum. God knows the last 2 are ripe as peaches.
