As mentioned you have to switch properties. I did this back about 3 years ago when I stopped traveling for about year and then started again. It corresponded to a stay 4 times and get a free night type promotion too so I was able to parlay building myself back up to Diamond and collect I think like 3 or 4 nights (there was a maximum). All the people knew me as I was checking in and out all the time. Big thing was sometimes I forgot which hotel I was in or what room and had to go ask the front desk