E.C.
You probably should ask your pediatrian; however, I do think that they need formula because of all of the iron, etc. It is recommended for at least a year for brain growth. My suggestion would be to maybe try a different formula or not give him juice at all. He really doesn't need the juice if he is getting fruit from another source. He probably prefers the juice because it is sweet. If formula is the only source of liquid - that and water. I would think he would eventually drink it since that is his only option.