If you like your current recipe, there's an easy way to thicken it up - add some cornmeal!
Because of the way a slow cooker (a.k.a. crockpot) works, very little moisture escapes and stews, soups, chilis, etc., don't "cook down" and thicken the way they usually do when cooked on a stove top. For chili, an often used and flavorful way to thicken it is to add a couple of tablespoons of uncooked, yellow cornmeal.
The amount of cornmeal you add depends on the quantity of chili; a big batch will require more, a small batch will require less. The safest way is to start with one tablespoon, and see what you think. If it's thick enough for you, you're done; if not, add more cornmeal. Sprinkle the desired amount of cornmeal over the top of the chili toward the end of the cooking cycle (about 10-15 minutes before you turn the temp down to the lowest setting just to keep the chili warm), stir it in completely, and let the chili finish cooking. It will thicken right up and taste great. (If, by chance, you make it too thick, there's an equally easy fix - just add a bit more liquid, such as water, beer, tomato sauce.)
I hope this helps you out -- Good luck!