Now that you mention it...my brother has a hop plant for fun, and it is covered with spider mites.
What makes you bring up the hops?
Powder sugar will knock down mites(the powder interferes with their little footpads) and trigger grooming, but I'm not aware of any studies about spraying sugar water.
There is a treatment called Sucrocide which is some kind of sugar (or derivative) mixed with water and sprayed on the hive bees, but that does something to the mites, not just trigger grooming.
I don't know anything about hops and have doubts that it would work, but it would be worth a try if you are interested.