If you have admin level access to the CMS for your account, you can edit your app name and image assets right in the CMS. Apps can be edited as long as your event start date is at least 28 days in the future. This time frame allows the edits to be reviewed, approved, and published in the stores before your event.
To get started, click on the event selector in the top right corner and then "Manage Users and Events" at the bottom.
On the next screen you'll see all the apps you have access to edit. Choose "edit app" to get started updating your app.
If you don't want to make edits to any of these items, you can click 'Next' to move on to editing your media assets.
On the next screen, you'll be able to edit your media assets including your app icon, iOS splash screen, and Android feature graphic. Please note the image requirements in the gray box near the top of the screen.
If you don't want to make any changes to your assets, click 'Next' to move onto the confirmation screen.
On the final screen, you'll confirm your changes.
Note that once you submit your updates, your app will be locked for editing until your changes have been published.