Haven't done archery for over 30 years, but as my arthritis worsened, I found I could shoot a borrowed 35# bow a lot better than my regular 55# ones. (This was before compound bows got popular.)
FWIW, there's an indoor archery range hereabouts I discovered recently:
http://www.rmsgear.com/Contact information
Address: 4298 Kipling St, Unit B, Wheat Ridge, CO 80033
Phone: 877-843-5559
E-mail: tlc@rmsgear.com
Don't know for sure, but I doubt leaving it strung for you and using it that way would reduce the overall weight enough to matter for your daughter. What might work better is for her to practice with it, thereby making her stronger.