"sentimentally woebegone" [Century Dictionary], 1768, lack-adaysical (Sterne), from interjection lackadaisy "alas, alack" (1748), a ludicrous alteration of lack-a-day (1690s), an exclamation of sorrow or regret, from alack the day (1590s). Hence, "given to crying 'lack-a-day,' vapidly sentimental." Sense probably altered by influence of lax. Related: Lackadaisically.
1711, up-a-daisy, baby talk extension of up (adv.). Compare lackadaisical. A word upsee was in use in English late 17c. in phrases such as upsee-Dutch "in the Dutch style" (of drinking), from Dutch op zijn, and also occasionally as an adverb, "extremely," and could have had an influence on this word.