I am like you, I don't increase my prices often enough, as I fear losing them, even though I have more work than I can cope with at present!
However, I bit the bullet with some last year and put one particular house up from £5 to £7.
I had been cleaning it for 5 years or more and this was the first time I had increased the price.
She was very respectful in the way she spoke to me, but just felt it was a big increase in one go. I agreed with her, and told her the only reason for this was that I had put off increasing the price for as long as I could because I really didn't want to have to put the price up, but unfortunately couldn't justify doing it for £5 any longer. I said that if I had increased it by 50p per year since I had been doing them, (what I should have been doing) the price would be more than the new price. She agreed and accepted the increase.
Had she not agreed to the increase, I would have said that I understood, but would invite her to find someone who would do the job for less than me, thank her for her past custom and leave it with her.
John.