The approval or conditional approval of a tentative map expires thirty (30) months after its original approval. This expiration terminates all proceedings, and no final map or parcel map of all or any portion of the real property included within the tentative map shall be filed without first processing a new tentative map. Upon application by the subdivider, filed before this expiration date, the advisory agency which originally approved the tentative map may extend this expiration date for a period or periods totaling not more than twenty-four (24) months after the original expiration date.