Unfortunately, I agree with tom. Junipers die in slow motion from the inside out. By the time it is showing significant damage outwardly, it is probably already a goner. You can check by snapping a few branches (since it is likely already dead, it won't matter). If they break off readily and are dry/ brown inside, they are dead. Scratch the bark on the trunk, see if you can get to moist green inside the trunk bark. If not, the whole tree is dead.
If you want to replace it, keep your juniper bonsai outside, year around. It is cold hardy well down into negative numbers and it requires cold dormancy in winter and does not tolerate warm, dry indoor environments.
If you want an indoor bonsai, look for something that is native to warm climates and does not require cold dormancy, like ficus, sagaretia, bird plum, Fukien tea, etc.
It makes me mad that there are so many unscrupulous dealers out there that only care about a quick profit, mass produce juniper bonsai from cuttings and sell them with no information or flat out wrong information ("sure, sure, you can keep this baby inside, it is easy, requires no care," or whatever else will help sell product).