LOS ANGELES (Reuters) - Simon Cowell and Fox television are gambling on pop icon Britney Spears and teen singer Demi Lovato to revive "The X Factor", but for many media watchers it could be a case of "Oops!..." did they do it again? Spears, 30, and former Disney Channel star Lovato, 19, are expected to bring in bigger, and more importantly younger, audiences when the singing contest returns for its second season on U.S. television in September after a weaker-than-expected debut in 2011. ...