Visit the folder where the media files that you want to re-analyze are.
You can see all your folders by visiting this page:
Once you are in the folder, select the media files that you want to re-analyze.
You can select the files individually:
Additionally, choose to use the top square checkbox on the first left column to select all files within the page view.
Pro-tip: at the bottom of the page, you can increase the "Items per page" to 100.
Once you've selected all the files you want to export, you can hit "Re-Analyze" in the top right corner.
It may take a minute to process. Once the re-analysis is done, all your insights will be updated across your account in both the individual files and the Explore Insights page.