((a)) At any time after confirmation of the plan but before the completion of payments under such plan, the plan may be modified, on request of the debtor, the trustee, or the holder of an allowed unsecured claim, to—

((1)) increase or reduce the amount of payments on claims of a particular class provided for by the plan;

((2)) extend or reduce the time for such payments;

((3)) alter the amount of the distribution to a creditor whose claim is provided for by the plan to the extent necessary to take account of any payment of such claim other than under the plan; or

((4)) provide for the payment of a claim described in section 1232(a) that arose after the date on which the petition was filed.

((b))

((1)) Sections 1222(a), 1222(b), and 1223(c) of this title and the requirements of apply to any modification under subsection (a) of this section.

((2)) The plan as modified becomes the plan unless, after notice and a hearing, such modification is disapproved.

((c)) A plan modified under this section may not provide for payments over a period that expires after three years after the time that the first payment under the original confirmed plan was due, unless the court, for cause, approves a longer period, but the court may not approve a period that expires after five years after such time.

((d)) A plan may not be modified under this section—

((1)) to increase the amount of any payment due before the plan as modified becomes the plan;

((2)) by anyone except the debtor, based on an increase in the debtor’s disposable income, to increase the amount of payments to unsecured creditors required for a particular month so that the aggregate of such payments exceeds the debtor’s disposable income for such month; or

((3)) in the last year of the plan by anyone except the debtor, to require payments that would leave the debtor with insufficient funds to carry on the farming operation after the plan is completed.