How to improve verbal score in 3 weeks

I am appearing for GMAT on 7/13. I have less than a month to prepare and need to improve a lot in verbal section. My Target score is 720+ but I am scoring between 640 and 670 in all GMATpreps I have tried so far. My Quant score varies between 48 and 50 but I am not able to score well in verbal. I scored around 30 in all the tests so far.

Any Tip/suggestion are welcome - Considering I have just 3 weeks , I get 3-4 hours max per day for studies, and English is not my first language.