You know your families and where they stand financially more or less. What you could do is use the rise in prices and ask for $1 a day that would equal $5 more a week which shouldn't be too much of an issue. Then when you replace next Sept raise the rates for incoming families again to put you where you want to be.

For those with school age in the summer I would probably consider asking for your usual fee plus an extra $3 for lunch since if they went to a summer camp they have to take their own lunch so parents would be paying for the food anyways.