Whenever the Planning Board or the Board of Appeals, after hearing all the evidence presented upon an application for appeals, under the provisions of this chapter, denies or rejects the same, each Board shall refuse to hold further hearings on the same or substantially similar application for appeal by the same applicant, their successors or assigns, for a period of one year, except and unless either Board shall find and determine from the information supplied by the request for a rehearing that changed conditions have occurred relating to the promotion of public health, safety, convenience, comfort, prosperity and general welfare and that a reconsideration is justified. Such rehearing may be granted only upon the favorable vote of a majority of the Board plus one.