I agree with everyone else that she is just bored of her food. We had the same problem with Zoey's last food - after awhile, she got bored of it and we had to start adding things to it or else she would skip meals. I eat a lot of chinese food, so I would add a tablespoon of warm white rice - if I had lots extra, I cut it into tablespoon sized peices and froze it, then just nuked a cube for 30 seconds before adding her kibble. If we had leftover meat, I'd add a bit of that. A splash of beef/chicken broth or a sprinkle of cheese were other ones we used a lot.
Once we switched foods, she started eating it without toppings again. I think she just likes the flavor of this food better for now.
One thing I would look into if you want to add meat toppings instead of having to cook hamburger all the time, check out dick van pattens food rolls. When we were still adding toppings, I thought about getting some of those to chop up and add on top.