77 Pa. Stat. § 772
A workers' compensation judge designated by the department may, at any time, modify, reinstate, suspend, or terminate a notice of compensation payable, an original or supplemental agreement or an award of the department or its workers' compensation judge, upon petition filed by either party with the department, upon proof that the disability of an injured employe has increased, decreased, recurred, or has temporarily or finally ceased, or that the status of any dependent has changed. Such modification, reinstatement, suspension, or termination shall be made as of the date upon which it is shown that the disability of the injured employe has increased, decreased, recurred, or has temporarily or finally ceased, or upon which it is shown that the status of any dependent has changed: Provided, That, except in the case of eye injuries, no notice of compensation payable, agreement or award shall be reviewed, or modified, or reinstated, unless a petition is filed with the department within three years after the date of the most recent payment of compensation made prior to the filing of such petition. Where, however, a person is receiving benefits pursuant to the act of June 28, 1935 (P.L. 477, No. 193), referred to as the Heart and Lung Act, the two-year period in which a petition to review, modify, or reinstate a notice of compensation, agreement or award must be filed, shall not begin to run until the expiration of the receipt of benefits pursuant to the Heart and Lung Act: And provided further, That any payment made under an established plan or policy of insurance for the payment of benefits on account of nonoccupational illness or injury and which payment is identified as not being workmen's compensation shall not be considered to be payment in lieu of workmen's compensation, and such payment shall not toll the running of the Statute of Limitations: And provided further, That where compensation has been suspended because the employe's earnings are equal to or in excess of his wages prior to the injury that payments under the agreement or award may be resumed at any time during the period for which compensation for partial disability is payable, unless it be shown that the loss in earnings does not result from the disability due to the injury.
77 P.S. § 772