I-797 expiry before L1-B Visa expiry

[shkraju]

Hello All,

My L1-Blanket Visa is valid till NOV2019 but my I-797 has Expiry in DEC2018. Passport is valid till 2022.
Do my employer has to apply for my extension in this case? Or Do I need to visit the consulate / travel out of US and re-enter to get a new I-797 date?

Please advice. Appreciate your invaluable response.

Thanks,
Raju