First you should have clear some concepts.
You don't burn fat on belly by doing abs, nor you don't make them visible by doing it. As it's said, abs are made in the kitchen.
Doing abs workout, what you do is make them bigger, as with other muscles.
You should focus your routine almost the same way you focus it for muscle gain, but introducing some more cardio. What is the really important part is the diet.
I would recomend you to read about basic nutrition and find elaborated diets to take as reference.
Edit - Info
As aditional info, here is a link to an article that talks about burning localized fat, and that quotes some studies, also providing the reason why localized fat can't be burnt. here is a small quote from the article:
More recently, in a 2007 study led by the University of Connecticut, 104 participants completed a twelve-week supervised resistance-training program in which their non-dominant arm was selectively exercised. MRI assessments of subcutaneous fat before and after the program revealed that fat loss tended to be generalized, rather than only occurring in the trained arm.
It turns out that there are a few basic physiological reasons why targeted fat loss does not work. The fat contained in fat cells exists in a form known as triglycerides. Muscle cells, however, cannot directly use triglycerides as fuel; it would be analogous to trying to run a car on crude oil. Instead, the fat must be broken down into glycerol and free fatty acids, which then enter the bloodstream. As a result, the fat broken down to be used as fuel during prolonged exercise can come from anywhere in your body, not just the part that is being worked the most.
Edit 2 - Additional info
After provinding this info that shows how burning localized fat is not posible, I have to clarify and also give part of reason to @DMoore, because in real terms, spot reduction is posible. This contradicts what I've just posted above, true? Yes and no. Spot reduction is posible but in a very very low way, let's say something around a 0.1%. So even this happens and even few people could have the genetics to burn a bit more localized fat, in general terms, this value is negligible to say that localized fat burn happens.