Green’s Dictionary of Slang

(orig. US) optimistic, positive.

1947		N.Y. Herald Trib. 26 Sept. 16: [heading] Dizzy Gillespie, Yardbird Parker, Thelonius Monk get nod in up-beat set.
1952		Variety 2 Jan. 5: ’51 was ‘Up-beat’ but ’52 looms as ‘Challenge Year.’.
1965		Punch 25 Aug. 275/2: Like Queen Victoria I am inordinately cheered up by the delivery of pieces of upbeat information, not merely about my own luck, but about others, even.
1975		L. Rosten Dear ‘Herm’ 127: If it had only had a more up-beat title.
1989		Kirk & Madsen After The Ball 211: Viewers would be treated to frowsy but upbeat moms and dads announcing telephone numbers.
1999		Observer Mag. 3 Oct. 29: They all look remarkably upbeat for convicted felons.
2000		Indep. Rev. 13 June 7: A typical upbeat track on side two.