It's probably overwatered. I don't know if it's wise to start fertilizing a stressed tree. Mine is outside yearround now because I tried one indoors and it died. They like the full spectrum of seasons (within reason of course). They also don't like wet feet. Mine is on my porch so that I control the water (we've been getting a lot of rain). It just started getting into the 90's here, so I may have to start watering more often, but I've only been watering ever 3rd day. I have used a water meter to determine when it is dry. Is yours still in the same soil it came in? Probably too much peat. My book may be wrong, as I have learned it often is, but it says to use a 60/40 ratio of aggregate to organic. I used decomposing granite sifted to 3/16" and rotting pine bark fines. It seems to be very happy. There are others who know much more than I, but this has been my experience.

It needs to be in a proper fast draining bonsai mix, which means mostly grit, with some 1/16" pieces of conifer bark, because the soil those 'bonsai' usually come in is potting soil with too much peat that holds water forever. If you know how to repot, do it quickly, because you only have a short time to 'get away with it' seasonally. If you don't know how, try to find a local bonsai club and they will help. Watering too often is the single biggest killer of newbie's junipers, and half that problem is just bad soil that the trees are planted in even before you buy them.

Should have had a chance to chill a bit over the winter, no?

"Never try to grow Junipers indoors, though they may seem to tolerate indoor cultivation at first, poor humidity, lack of light and dormancy will eventually kill them. Do not trust a vendor, seller, book or website that claims Junipers can be grown successfully indoors! Dead Junipers can continue to display normal foliage colour for weeks or even months after they have effectively died. "

Here is a link that might be useful: Juniper culture