I found this response to a similar question on Parents.com:
Question
My 3-month-old baby does not want to feed (bottle or breast). I offer every 3 to 4 hours but it doesn't seem as if she's drinking very much. If she does take the bottle, she will only have 16 ounces a day. Is something wrong?
Answer
The average baby takes 2 or 3 ounces of formula each day for every pound of body weight, up to a maximum of 32 ounces. A newborn weighing 7 pounds will take an average of 14-21 ounces of formula in a day. A 4-month-old weighing 14 pounds needs 28-32 ounces.
Kids have a very strong thirst mechanism so healthy kids tend to get plenty -- as long as they are not fooled by getting too much juice or water. Juice can be a useful medicine for constipation, but it is not a healthy food at her age.
They get much more efficient at getting breast milk by her age so she will likely get more in less time than she used to.
If kids don't have a wet diaper in 8 hours, are not growing, or don't seem satisfied, they should be checked. Otherwise, relaxing is a good plan.