https://www.uscis.gov/sites/default/files/USCIS/Resources/C1en.pdf
How do I apply to extend my stay in the United States?
Application procedures for an extension of stay depend on your
nonimmigrant status:
• Employment-Based Categories: If you are in one of the
following employment-related categories, your employer should
file a Form I-129, Petition for Nonimmigrant Worker, before the
date your Form I-94 expires:
E-1 or E-2 (Treaty Traders, Treaty
Investors, and Employees
of Treaty Traders and
Treaty Investors),