When a dog pushes his food around, this is his way of saying he is bored with his food. Sometimes dogs need a touch of variation. You may want to begin introducing new foods into his diet such as veggies or some chicken. You can give this in small amounts.
There are also dog gravy's that can be purchased at your local pet store. This can be mixed up with his food to give it a new flavor and help end the dreary days of same old dog food.