I have the dog dishes, one was full, now empty, how do I fill the dog dishes..

Click on a sim then click on a bowl. Choose fill bowl.

You can not send the dog to the bowl. The dog goes there by itself then usually will run out and dig treasure.

When your sim is doing a task, click on the dog food bowl and click on "call over" and your dog will go to it. You may have to do it a few times before you get your dogs attention

I bought the dog bowl. The dog came over on it's own and ate. Pick any sim then click the bowl. Select fill bowl.

Choose an Adult sim, preteens and younger can only call the dog over to eat or drink, then press the bowl, then press "Fill Bowl".

U click on the bowl. Then click fill bowl. Then click call over 5-6 times and the dog will come and eat it. It's that easy!!!!!

In the Sims free play this is how I do it. Put dog bowls in inventory by clicking furniture store button. Then place bowl back into world, then it will refill

Apparently it doesn't work with babies, toddlers or kids... Must be an Adult to refill the bowl I guess, but I was struggling at first as well.
Click on an Adult sim and click on the bowl and the option for you to refill your bowl should pop up.
Simple as that, really!
Then get your sim to call the dog to your bowl and they should eat it!!
Hope that helps :3

You just tap on the bowl and click refill