I would call the First Time Homebuyer Credit number to verify that there is indeed a credit in the account and that no further payments are due.
https://www.irs.gov/credits-deductions/individuals/first-time-homebuyer-credit-account-look-up
If so, this would mean that there was an overpayment (most likely in the last year you paid it) and I would ask them what they recommend would be best for your situation.
They may advise you to amend the previous return for the last year you repaid the credit in order to get this balance refunded to you.
