No one can make you pay a debt that has been discharged, but you can voluntarily pay any debt you wish to pay. You do not have to sign a reaffirmation agreement or any other kind of document to do this. You do not have to pay a secured claim if the debt is discharged, but the creditor can still take the property. For example, you may want to work out a plan with the bank to keep your car. To promise to pay that debt, you must sign and file a reaffirmation agreement with the Court.
Reaffirmation agreements are under special rules and are voluntary.
They are not required by bankruptcy law or by any other law. The agreement will not be legally binding until the court approves it. If you reaffirm a debt and then fail to pay it, you owe the debt the same as though there was no bankruptcy. The debt will not be discharged and the creditor can take action to recover any property on which it has a lien or mortgage. The creditor can also take legal action to recover a judgment against you.