The Planning Board shall act within the applicable time period set forth in this chapter, computed from the date of submission of a completed application at a regular meeting, or within such further time as may be mutually agreed upon. If the Planning Board approves the final plat, a notation to that effect shall be made on each plat, signed by the Chairman and Secretary of the Planning Board. Failure of the Planning Board to act within the allotted time or a mutually agreed upon extension shall be deemed to be favorable approval, and the Township Clerk shall issue a certificate to that effect.