Is there a reason that you must keep it in the house? Junipers live outside.. they are trees... and you insult their egos if you make them into house plants
Really, sunlight and breezes, cool nights and warm days are what the tree craves right now. That is what it needs to live. Morning sun, dappled afternoon shade would work wonders.
Look for bugs... it's early for spider mites but if it has been in the house, it might have some. Spider mites can cause browning and sickly green colors. Search this forum for "spider mites". But don't treat the tree unless you find some.
Joanie