+1 just boil it down

I would just simmer on stove without lid to reduce, too. Add more seasoning if needed.

Don't add water.

Simmer it on the stove top in a pot until the liquid has reduced. I'm sure it will be fine.

I would just cook it down on the hob.

I would take some masa - and add it to water to make it a thick paste - then add it to chilli (giving each addition ample time) until you like the consistency. The masa will also give it a tad of a mexican flavor......

If it's already done, you can remove some tomato with a spoon (assuming its veggie chili, just take a 2c quantity of the all soup) and put in a blender or use a potato masher to make more liquify, then return to the cooker. If it's mid-slow-cook, wait until it's done. Remember chili is always better day 2 anyway!!

I substituted a 28oz can crushed tomato with 2-15oz diced tomato because that's all I had and instead of cooking it on the stove, I used the slow cooker. It's looking rather soupy and not thick the way chili is supposed to look.

What now?