After drinking it for the first time, juice accounts for 3/4, and water accounts for 1/4.

After drinking for the second time, the juice accounts for 3/4*3/4=9/ 16 (imagine the remaining juice after drinking for the first time as a whole, that is, bring it in as "1").

After drinking for the second time, the water ratio is 1/4*3/4=3/ 16 (the same idea as above).

When drinking for the third time, you should add 1/4 water to make it 3/16+1/4 = 7/16.

Then the third juice is 9/ 16 and the water is 7/169/16+7/16 =1.

Therefore, no matter how much you drink for the third time, there is always more juice than water.