I have had the same situation several times, started with one room, and now have 4, and am considering another. You just have to 'suck it up buttercup' and start all over with the reviews. I find that dropping the price for a while to get the bookings in quickly helps, then the reviews follow. Then you can increase the price to your normal level. As others have said, guests can see that you have other listings and can read those reviews also. Also mention 'this is the second of my bedrooms to be listed, and I would encourage you to look at the reveiws for the first one' in the description.