It appears that your child has a condition called Ichthyosis which is genetically inherited dry skin. Another possibility is that such dry skin could be the fore-runner of another condition called atopy.
Whatever the cause she certainly needs continous use of moisturizers until adolescence.
Please note that the external moisturizers should be applied correctly. After a cold water bath using minimum soap, the child is dabbed dry and not rubbed dry. The moisurizer is then applied all over the body, and allowed to dry before the clothes are worn.
Natural moisturizers like aloe vera are also available as market products.