Although this article states that the company hoped to eventually resume, the broadcasts apparently never restarted.
Cleveland Plain Dealer, May 29, 1919, page 9:


Navy  to  Assign  New  Wave  Length  for  Sending.

    At the request of the navy department, the wireless concerts which have been sent out each Thursday evening by the Glenn L. Martin Co. have been suspended until a new wave length can be assigned for the purpose.
    It was found that the wave length used in sending the phonograph concerts conflicted with the navy wave length and it was feared there might be interference with the government messages. It has been found difficult to assign a new wave length because many other governmental departments have not yet been assigned wave lengths for their own use.
    The concerts, which were heard by hundreds of amateur wireless experimenters in this territory, will probably be resumed in the near future.