You appear to be using a new AppleID account - and your iPad remains associated with your original AppleID account.
Creating a new AppleID account is a particularly bad idea - as you will encounter Activation Locks and lose access to any paid Apps and services purchased using your original account.
If your primary email address needs to be changed or updated, instead o creating a new account, you simply need to update the AppleID account that you already have:
Change your Apple ID - Apple Support
Change your Apple ID password – Apple Support
What to do after you change your Apple ID or password - Apple Support
If instead you wish to use an entirely different AppleID account, you must first recover the credentials of your original account. Your credentials can be recovered here:
https://iforgot.apple.com/
To recover your credentials, you’ll need access to any one of the following:
- Your primary email address mailbox that corresponds with your AppleID
- Any of the secondary/recovery email addresses that should be configured for your AppleID account
- Any of the trusted telephone numbers (fixed line or Cellular/Mobile) that are associated with your AppleID
Unless you AppleID account has not been fully/correctly configured, or has been seriously neglected, recovery of the AppleID and password should not be difficult.
More information about recovery of your AppleID:
If you forgot your Apple ID - Apple Support
More information about recovery of your AppleID password:
If you forgot your Apple ID password - Apple Support
When you recover access to your credentials, you would be well advised to log-in to your AppleID account from a web browser - and verify/update any email addresses and trusted telephone numbers:
https://appleid.apple.com/
