You can change the email address associated with an Apple ID - the one used to receive receipts with purchases, etc. without having to create a new Apple ID.
All apps, all paid and free apps include DRM protection that is tied to the iTunes account or Apple ID that was used to download the apps. In order to install an app update for an app that was downloaded with your former Apple ID, you will need to use that Apple ID and password.
Settings > iTunes & App Stores > Apple ID.
Select the Apple ID and at the menu window that appears select Sign Out.
Sign in at the same location with your new Apple ID.