I am a firm believer that if you don't want/like the pet you have then re-home it to someone who will enjoy it and take care of it properly. I know even though you don't want your Beardie you want a good home for it because you obviously care for it. I would advertise your Beardie on any local sites or newspapers and see if you get someone that is interested. Make sure you quiz them on what they know of the Beardie before you sell it to them though, and give them any tips/ideas you have from owning the Beardie in the past.
As for getting the new pet, snakes are wonderful to own (I have a corn snake) but you also need to know what it involves in owning one. Do your research and make sure it's alright with your parents