A certificate may be renewed from time to time and the provisions of this Act and the rules made thereunder (including provisions as to fees) shall apply to the renewal of a certificate as they apply to the issue thereof:
     Provided that no certificate shall be renewed unless, the application for its renewal is made not less than three months prior to the date on which the certificate, would, but for such renewal, cease to be valid:
     Provided further that the registering authority may entertain an application for the renewal of a certificate which has been made at any time during the period of three months prior to the date on which the certificate would, but for such renewal, cease to be valid if the applicant satisfied the registering authority that he had sufficient cause for not making such application before the said period.