Hi forumuser1,
My advice to you is, please visit a nearby DIS office and tell them that you have new I797 but the immi. officer gave you I94 till old 797 only.
Depending on the mood the officer, they can extend the date based on latest I94.
I now 2 instances of the scenario, wherein the person when entering US did not show (or showed but did not help) and immi. officer gave I94 till visa expiry. Then these 2 ppl went to CBP office in Phili, PA airport and got the I94 date extended based on their latest I797.
You can also try doing the same thing.
Regards,
HK