im with leigh about the spider mite, it looks like the issue i have had in the past, it could also be a sun problem, junipers should be getting at least a minimum of 5 hours direct light a day, and preferably not the midday sun either, if you can get it in a spot where it receives morning light until 10 or 11AM the shade or part shade til 2 or 3pm then full sun for the rest of the day would be very beneficial, mine get a lot of sunlight, upwards of 8 hours or more
if it is spider mite try and do something as quick as possible and if you have other trees keep it away from them for a while, you should even check the others just incase, i lost 2 junipers and am inbetween saving another as i had an attack of spider mite and the little buggers infested three of my trees, it was too late for 2 of them, and like i said the other one seems to be hanging on but just, i have lost 3 years of development on it too.
jamie