As an authorisation manager, you can easily issue new chain authorisations or renew existing ones via My Reconi. So first log in to My Reconi.
Choose "Chain Authorisations".
Then choose the "Issue chain authorisation" option.
Start the renewal via the renewal button behind the authorisation or click on "Renew chain authorisation" at the bottom of the page.
Are you not (yet) an authorisation manager?
If you do not have manager authorisations, a new application must be submitted for renewal.
To the step-by-step plan for granting chain authorisation to an intermediary (form A)