Once an app is released, or if it's rejected during the review process, you can't make changes to the app. However, you can create a new version of it.

When you create a new version of a released app, both versions of the app appear in the Developer Portal until you release another new version. When the new version is released, the previous version is no longer available.

If you create a new version of a rejected app, the new version of the app is displayed instead of the previous version, and the previous version is no longer available.

An app can have, at most, two versions: the current version and the previous version.

Create a new version of an app

Log in to the Developer Portal.
Navigate to the Your apps page.
Click Create a new version.

Creating a new version of an app creates a complete copy of the existing app, including its metadata. Nothing is lost between versions.