It will be sweeter but I wouldn't suggest cutting back on sugar. The sugar is a necessary component in the cookie, usually giving colour and pliancy. Remove the sugar and the cookie can be very dry and stiff. I'd reconstitute the juice and use the amount of orange juice the recipe originally called for. I'd skip the part that called for zest.
If you serve your children oranges from time to time, perhaps you'd consider zesting the orange before you peel it for them. Put the zest into a baggie and simply freeze it. You can keep removing the same baggie each time you zest an orange, just adding to the original batch.
How can we sleep while our beds are burning???