Once a Trend radar has been published, managers with admin rights to the Trend radar can still make changes to the Trend radar, as well as deactivate it or delete it. You can enter the edit mode via the Triple Dot menu at the top right in the Trend radar view, and from there add more trends to the existing radar, for example, and reactivate the survey.
Write a message to the participants and ask them to evaluate the new trends or evaluate them by yourself. Then deactivate the survey again and update the Trend radar in step 4 “Finalisation”.