The easiest way to raise rates with out much if any backlash from your customers is to raise them the same as the governments cola raise for SS benefits. Do it around the 1st of the yr and just tie the price increase in with the cola raise the government figures. And send the letter with that reason and maybe a small article about how much it will be. I think its around 2.9 % this yr. Most people won't argue with the logic as they know that cost have gone up. And seniors would have just received there raise at that time so in essence your price would stay the same. But at least your not losing more money by not raising prices.