LINCOLN CENTER'S `SERIOUS FUN!' returns to Alice Tully Hall for its second season, July 14-Aug. 4. The schedule of performances (expanded to 16 from last year's 12) will feature Michael Nyman's chamber opera ``The Man Who Mistook His Wife for a Hat,'' plus specially commissioned works by a variety of composers, choreographers, and performance artists. PUBLIC TELEVISION STATION WNET, Channel 13 in New York City, will feature news and public-affairs in prime time as part of its fall schedule. ``The MacNeil/Lehrer Newshour'' will move from 7:30 to 8 p.m. beginning Sept. 5. And on Sept. 12 the station will begin airing, at 11 p.m., a nightly Bill Moyers report on the presidential campaign. `ENCOUNTER: THE SEARCH FOR EXTRATERRESTRIAL LIFE,' a new sky show at the American Museum-Hayden Planetarium in New York, presents a detailed look at the search for life in space. Actor Mark Lenard, who played Spock's father in ``Star Trek'' films, will narrate.