You can continue to extend your H-1 even after I-140 is revoked by the employer, IF, the revocation was sent more than 180 days after I-140 approval.
Under AC21, you do not have to start a new green card if:
1. Your I-140 is approved;
2. Your I-485 has been pending for 180 days or more;
3. You will take an employment same as or similar to your green card job; and
4. You file Supplement J.