Juice therapy is effective in curing many gastrointestinal disorders but the body metabolism and functioning certainly gets affected by the same. Hence the question.
My personal experience is that while fruit and vegetable juices are nutritious and have beneficial health effects, normal intake of juices with limited water content may not have any significant effect on the quantity or frequency of urine in normal human beings. I do not know whether any of these juices have marked diuretic effects.
On the other hand, consumption of water frequently may increase the frequency of urination and urine output. Therefore, I feel frequent consumption of juices may indirectly influence urine output through their water content. These effects may depend on season also. In rainy season frequent urination even with consumption of small amount of water is not uncommon. Frequent urination is also common in elderly people and diabetics.