When a debtor files for bankruptcy, chances are most or all debts will be discharged (no longer due by the debtor).  The creditor has no further rights with regard to the discharged debt.

In some instances, the debtor may choose to repay a discharged debt.   A common reason is to be able to continue to do business with the creditor.

If the debtor and creditor both want to make the obligation binding, they can enter into a reaffirmation.  This creates a new agreement which is not bound by the prior bankruptcy discharge of that debt.