Hi Rishabh.
To score 680, you need to get around Q47 and V36.
So, you need to get around 18/28 counted Quant questions correct and around 21/30 counted Verbal questions correct.
In other words, you need to get around 64 percent of the Quant and 70 percent of the Verbal questions correct.
Accordingly, to achieve your score goal, you have to increase your practice accuracies, and you could shoot for the following:
Quant
E - 90%
M - 70%
H - 60%
Verbal:
E - 90%
M - 80%
H - 70%
To achieve those higher accuracies, you can work on one topic at a time and practice untimed until you learn how to get the questions correct consistently. Then, once you're consistently achieving high accuracy untimed, you can work on speeding up to test pace.