Reports remain in your account for as long as you need them. To find previous ones, go to the Reports tab:

The reports page will open to the currently active room, showing your most recent activities sorted by date. Click on each column to sort the reports by name, date, room name, or type. You can also search for specific reports using the search bar on the left or use the filter option as well on the right to find something specific. 

Here, there are a variety of ways in which you can filter or search for reports on this page. Begin by clicking the filter drop-down box on the top right and selecting the criteria or room in which you would like to search.

The filter option sorts separate rooms and will show the number of reports available in them. Scroll down the menu to find the All section for your active or archived reports. Any reports from deleted rooms will also be available. If you deleted any reports, they'll go into Trash and will remain for 30 days and be able to be restored if needed, before being deleted permanently.