If you know other charity quilters, perhaps you can trade projects with one of them who is in a similar situation. That way the charity still gets their quilt, your enthusiasm may be rekindled with the new project, and you don't end up with another UFO. I have finished other people's abandoned projects, and while I could see why they abandoned it and the finished quilt was not perfect, it still made a nice quilt that was enthusiastically received by the giftee.