OLNEY, Md. — Jason Loewith, a director and librettist (“Adding Machine”) and head of the D.C.-based National New Play Network, has been named artistic director of the Olney (Md.) Theater Center, the 75-year-old facility outside of Washington, D.C.Loewith succeeds Martin Platt, who ankled in December by mutual consent with Olney brass after only seven months in the post. Loewith, 44, is a former a.d. of Next Theater in Evanston, Ill., where he produced “Adding Machine” during the 2006-07 season before it went on to win acclaim Off Broadway. Since 2009, he’s honchoed the NNPN, the alliance of more than 20 nonprofit theaters that recently relocated to D.C. Olney, which has three stages, debuts its 75th anniversary season this month with the tuner “Spring Awakening,” to be staged by Steve Cosson, founding director of the Civilians. It will also mount “A Chorus Line” this summer. Loewith will depart his NNPN post but will continue this year as head of a new NNPN project called the New Play Exchange, which the org hopes will shake up how playwrights and nonprofit theaters connect. The Doris Duke Foundation has granted NNPN a $110,000 two-year award to support the design, development and pilot of the new Web-based Exchange tool. It will combine crowdsourced recommendations, social-media functions and a new play script database.