Have you tasted it K.? Formula tastes gross... all the corn syrup in the world doesn't mask this.
Since she is self-choosing food over formula, follow her lead. Give her water - which is healthier than formula - and offer her a liquid supplement like EmergenC or others (there are many)on a spoon or cup. Offer her milk, goat's milk or soy milk to see if she like these things - all are fortified.
Formula is simply a carrier for supplements to help a baby grow and develop. As a food it is neither healthy nor normal ~ it has fillers, corn syrup, and way more supplements than most babies need.
Consider: breast milk is not fortified and yet allows for a baby's growth and development easily :o)