Take a look at Ralph Vaughan Williams’ lovely “Six Studies in English Folk Song” composed in 1926 for cello and piano – I feel pretty sure that at least some of them could be adapted for lever harp, even if it means in a few passages only playing the bass-clef line, divided between both hands, or simplifying somewhat. Worth checking out, anyway: there’s plenty of info out there if you google it.
You can listen to some free snippet-samples on this site, though it means enabling their media player, which I didn’t, so I haven’t actually heard these particular examples. You’ll probably find loads on YouTube too. It’s beautiful music.
http://www.classicalarchives.com/work/56577.html#tvf=tracks&tv=music