Did you already start digging it up?
Because depending on how long you've been adding things on top, you might find that earthworms already "tilled" it for you. If they did, I'm sure you will know within the first few shovels' worth, and then you can decide if it's really worth the effort of...
You may already be doing this, but any time you need to dump the chicken water, or wash out the waterer, do it in the run (or somewhere else you want water to be.)