In case where registration is cancelled suo-motu by the proper officer, the taxable person can apply within 30 days of service of cancellation order, requesting the officer for revoking the cancellation ordered by him. However, before so applying, the person has to make good the defaults (by filing all pending returns, making payment of all dues and so) for which the registration was cancelled by the officer.
If satisfied, the proper officer will revoke the cancellation earlier ordered by him. However, if the officer concludes to reject the request for revocation of cancellation, he will first observe the principle of natural justice by way of issuing notice to the person and hearing him on the issue.
Source: CBIC Website