If your app submission requires major changes, then it will be rejected. You receive an email titled Important: [Your app name] app review has been rejected that outlines the required changes you need to make before re-submitting the app for review. When you receive this email, your app is marked as Draft in your app listing dashboard. After you've made these changes to your app, you can resubmit your updated app through the Partner dashboard, at which point it will be screened as a new submission.