My advice would be not to compromise. Put the price up to what it should be, not somewhere inbetween. If they say anything, trot out the old "It's the reason he passed it on" speach.
I had to do this with some I got from a retiring shiner. There was the odd loss but any loss is negated by the price rise.
When mine go up I tell them that the price is fixed for 2 years and also remind them of the last increase, which is now over the 2 year mark.