In most of the cases I have seen children are suffering from this problem.The main causes like any early age infection infection like jaundice
,shkir-dosha,worms,mental induced stress
,wrong food/drinking habit etc.Any laxative doesn't work for maximum period because of unknown pathology. In many cases its very tough to recognize the basic cause.
In your child's case,low appetite is the basic cause.She likes orange juice,means vayu vikruti is there i.e. the medicines for vayu anuloman are required.Any type of candies make stools harder.
Food must be easy diagestable,warm served,prepared with happy mind,served at the time of appetite,one should (you)know the properties of food,having the food at calm place etc are the basic rules about having food according to ayurveda. 90% constipation
habits are solved who follows these rules;this is my experience.In children,the mother should follow these.
Personally,I suggest not to do any yogic kriya as your child is only 2 years old.After 8-9 years she should try some yogasanas. Proper medical guidance from experienced vaidya is important.