Try mixing a spoonful of plain yogurt in her dry dogfood. Also the yogurt helps with gas.
When Bayleigh went through the picky stage I made a gravy to pour over her dog food. I boiled carrots, celery, mushrooms, and a boneless skinless chicken breast in broth. When veggies and meat were tender, I ran through the food processor. I would add a couple of spoonfuls over her food each time.
Or sometimes I would sprinkle a little shredded cheddar cheese over her food!