I find my kefir to be rather tough going,actually!
It does fine with not changing the milk for a week at times, at least in winter (makes the kefir very tart, but doesn't seem to harm the culture) and it will happily go 'to sleep' in the fridge if we are away for a week or two. It might need an extra milk change after that to properly 'wake up', but it does go back to normal.
If you think your culture is damaged/tired changing the milk more often (up to twice a day) and a bit of patience will most likely revive it. Give the 'not quite right' kefir to the dogs during that 'reviving 'time.