Every application under sub-section (3) of section 13 of the principal Act as it stood immediately before the commencement of this Act, which is pending before an arbitrator referred to therein shall, on such commencement, stand transferred to the appellate authority to whom an appeal could have been preferred under the principal Act as amended by this Act if the amount to which such application relates had been determined by the competent authority under sub-section (1) or sub-section (2) of the said section after the commencement of this Act, and such appellate authority may deal with such application from the stage at which it stood transferred to it as if it were an appeal pending with him:
     Provided that either of the parties to the case may demand that before proceeding further, the previous proceeding or any part thereof be reopened or that he be re-heard.