Leslie- According to a time line of construction and reconstruction on the Notre Dame de Paris website (http://www.cathedraledeparis.com/Building-history) 
the first time is was reconstructed after the initial 100 years of construction in the 12th and 13th centuries was in the late 13th century and extending into the 14th. The large flying buttresses and choir apse were added. Then again in the 17th-18 centuries reconstruction was needed after some destruction during the French Revolution. There have also been restoration projects during the 19th and 20th centuries.