I have valid visa for 3 years but when i came to USA, my passport was expiring in 1 year only. So i got I-94 validity as matching to my passport. Now i have got a new passport so can i travel to mexico by air and come back again and will it give me a new I-94 ? I dont want to go to india and come back but instead looking for Mexico since there is no Visa required for Mexico. Please help.
Yes, you can get a new I-94 by leaving and reentering the US. It is not necessary to travel to India.
When you return, you can point out to the officer that your previous I-94 was limited because of your expiring passport, and that you now have a new passport. This will reduce the chance that you will be readmitted on the basis of your old I-94.
Another option is to file an I-539 application to extend your status. If it is successful, you will get a new I-94 from USCIS.
The current filing fee (May 2018) is $370, a cost that seem worthwhile if you are hoping to avoid an otherwise unnecessary trip to Mexico, or much too high if you were planning to go to Mexico in any event.