It is necessary to renew trademark registration as it has a validity of 10 years. Trademark registration renewal can be done beginning from 6 months before the date of the expiry. A notice for trademark renewal is sent before the date of expiry.
If an individual / organization fails to renew the trademark then the registrar may remove the trademark from the Trademarks journal. But again this happens only after 12 months after the expiry date. Between 6 and 12 months after the expiry trademark registration can be renewed on payment of a fine through following the restoration a process.