Media General Inc. said Monday its earnings increased 16% in the first quarter due to sharply higher results in its newspaper and television operations. For the period ended March 27, the company reported earnings of $ 3. 9 million, or 15 cents a share, compared with earnings of $ 3.4 million (13 cents) for the comparable period last year.Revenues for the 1994 first quarter were $ 149.4 million, up 4% from $ 144. 2 in the same period a year ago. The company publishes newspapers and operates television stations. Media General’s stock was up 37 1/2 cents to $ 22.87 1/2 in late afternoon trading Monday on the American Stock Exchange. Regal Cinemas Inc. has completed its $ 24.5 million cash purchase of 13 theaters from National Theater Holdings Corp., of Cleveland. Most of the theaters are located in Cleveland, Akron and Youngstown, Ohio. With the purchase , Knoxville, Tenn.-based Regal Cinemas now operates 61 theaters, with 454 screens, in 10 states.