Create Your Signing Certificates
Ensure you are signed into your Apple developer account through Xcode, which can be done through Xcode > Preferences.
From Accounts, you're able to Manage Certificates and add new. From the lower-left corner of the signing certificates sheet, click the Add button (+), and choose a certificate type from the pop-up menu.
Please make sure to create an Apple Development and Apple Distribution certificate.
NOTE: When your Mac asks you for permission to create the certificates, select ALWAYS ALLOW.
For additional information about creating, viewing and exporting signing certificates, read Apple's documentation HERE.
From your General settings, you will need to increase your version prior to proceeding with the resubmission.
Archive Your App
In Xcode, switch from simulator mode to Generic iOS Device.
Next, click on Product and select Archive.
If the archive builds successfully, it appears in the Archives organizer. The Archives organizer is a pane in the Organizer window that you use to upload your app to App Store Connect. To open the Archives organizer, choose Window > Organizer and click Archives.
To complete the upload of your app to App Store Connect, click the blue Distribute to App Store button.
Choose the Build Before You Submit
Navigate back to the My Apps section of App Store Connect.
Select (+) Version or Platform to add a new version of your tvOS application.
Before you submit an app to App Review, you will need to choose the new build (from all the builds you uploaded) that you want to submit.
Note: Please allow around 30 minutes for processing before the build is selectable in this view. Look out for an email with the subject of "App Store Connect: Version [version] for [app_name] has completed processing".