Hello Slongshot,
Welcome to Apple Support Communities. We understand that you're unable to update your payment information. Since you received a new card, it should have a new number and expiration date. To that end, let's add the card as a new payment method using these steps on your iPad:
1. Open the Settings app.
2. Tap your name.
3. Tap Payment & Shipping. You might be asked to sign in with your Apple ID.
4. From here, you can do these things:

• Add a payment method — Tap Add Payment Method.
Once the new card has been added, follow these steps to remove your old card:
• Remove a payment method — Tap Edit, tap the red Delete button, then tap Remove. If you have an
unpaid balance, have subscriptions including an iCloud storage plan, or you use purchase sharing,
you can't remove all payment methods. Learn how to remove all payment methods.
This information can be found in the resource you were reviewing, Change, add, or remove Apple ID payment methods
Let us know if this helps.
Best wishes!