H1B visa Valid till July 2018, Have 797 with same employer till july 2020 - Need Restamping ??

Dear All,
Please Help !!!

Last year my Passport was expiring so got less I94 even my visa was valid till july 2018, after that I got new passport and my employer filled Extension to avoid any issue and I got 797 with I94 till July 2020.

Now I am travelling to India between 10 Nov- 25 Nov, should I do re-stamping so that on new passport I get visa till 2020 and when I enter I get I94 accordingly.

what happen if I do not get stamping (dropBox 8 business days due to thanksgiving) and come back will I get I94 as my Visa Expiring on july 2018 and again I need to file extension even I have Approved 797 with I94 which I mentioned above.