Can I have the same juice twice in the day?

If it is a vegetable juice (for example green juice, ash gourd juice, cucumber juice, carrot juice), you can have it twice, or even thrice a day. However, if it is a fruit juice, please limit it to only one glass a day.

Bear in mind - you are on a fast. It's not good to needlessly drink too many glasses of juices if there is no physical need for it. Only drink when you are hungry.