Your business is your data base..... end of, thats it. You can have as many shiny truck mounts, Rotos portables, etc etc as you like,but if you have no data base you have no business, so you have to grow it,nurture it and market to it regularly.That includes non converted prospects.
I would DM your entire data base,past and present. I do not agree that you should only send to those that spent with you previously, how on earth would you get any growth if you did that ?