§ 13. Reclassification of disabilities. Subject to the limitations in section fifty-one of this chapter and in section one hundred twenty-three of the workmen's compensation law as made applicable to this chapter by section fifty-seven of this chapter, the workmen's compensation board may at any time, without regard to the date of the injury, upon its own motion, or on application of any party in interest, reclassify a disability upon proof that there has been a change in condition, or that the previous classification was erroneous and not in the interest of justice.