Source, in full
Widely attributed to Chaplin and a few others, research done for "A Day Without Laughter is a Day Wasted" at Quote Investigator indicate that such expressions date back to that of Nicolas Chamfort, published in "Historique, Politique et Litteraire, Maximes détachées extraites des manuscrits de Champfort" Mercure Français (18 July 1795), p. 351: La plus perdue de toutes les journées est celle où l’on n’a pas ri. Translations of this into English have been found as early as one in "Laughing" in Flowers of Literature (1803) by F. Prevost and F. Blagdon
Notes from Wikiquote
I admire the man who exclaimed, “I have lost a day!” because he had neglected to do any good in the course of it; but another has observed that “the most lost of all days, is that in which we have not laughed;” and, I must confess, that I feel myself greatly of his opinion.