GST No. cancelled want revoke

1] My clients is Logistic Firm.  

2] Monthly GSTR3B till August 2020 have been filed

3] Monthly GSTR1 till Nov 2020 have filed

4] Due to delay in submission of return GST Maharashtra office  have cancelled GST no. wef 16/12/2020

5] Now after 90 day from Cancellation Order Firm want to filed GST return regularly.

6] Since after 90 days we can't filed revocation of application through online. 

7] Please guide us or know the procedure how can we revoke GST no. and file pending return.

Thanks in advance.