Hello cortneyh13,
We understand you aren't able to make an in-app purchase on a game app with your iPad. You mentioned already restarting it and that hasn't helped. You might need to verify or update your payment method associated with your Apple ID. Start here: If you need to change or update your Apple ID payment method
Make sure the information for your current payment method is correct, like the billing address or card information.
Update your payment method on your iPhone or 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. Tap Add Payment Method, enter the new payment method, then tap Done.
5. Tap Edit.
6. Tap the red delete button next to the old payment method, then tap Delete.
Once you've confirmed the payment method shows correct, test downloading a free app from the App Store to see if it's just in-app purchases or all content from the App Store. Reply back with how it goes.
Best regards.