My kids thankfully haven't experienced glue ear, however we have had wonderful successes with a homeopath for various childhood complaints, and I can't see why homeopathy wouldn't work for glue ear as well.
I am a naturopathy student, and whilst I live (and swear by) naturopathy, I find homeopathy a bit better for young children, as a lot of herbs unfortunately taste pretty awful, so compliance can be an issue. Nevertheless, a naturopath (and indeed a good homeopath) will probably recommend some dietary changes to work on her mucous congestion, such as avoiding dairy.
HTH