To update your apps, login to Marketplace and then go into your dashboard and view your “Items” under MY UPLOADS. Find the app you need to edit and click the edit pencil icon on the right. Go through the app upload flow and update the fields you want to change. Once complete, click "submit for review" and one of the Marketplace admins will review your app changes and publish your updated app.
The link above takes you to the Application Development marketplace dashboard. If your apps are in a different marketplace like ITOM, Fortify, or ArcSight, then use the alternative links below.