Unfortunately today's products only have 20 - 30% deet in them.
I've used products with deet for years. Many years ago (maybe 40), I stopped putting it on my skin. Put it on your hat, and on your clothes around your collar and on the shoulders and back. Typically I identify one or two bush shirts and I basically don't wash them. Each time I go out, I "add" more deet to the clothing. And, throw the shirt away (or wash it) at season's end.