We just released an update that auto archives your discussions after 30 days in all of your projects. This used to be a manual process where you needed to archive each discussion topic individually. This makes managing discussions much easier and now you only see recent and ongoing discussions. Archived discussions can be accessed by clicking the Archived button on the gray filtering bar as shown here:
Discussions are reactivated automatically if they receive a new comment. This allows you to always see the latest replies from within the Discussions section. If you need to, you can also use the search to easily find an old discussion. To learn more about auto archiving in your project management app, visit the support center.