Here is something that would help you decide what to do about your tree:
Try to do a sketch of how would you like this tree to look like, in its final form - based on the current picture, of course.
The drawing should have the general shape, main branches, as well as the right proportions (trunk thickness, etc.).
Then ask yourself, is this image achievable in the next 5 - 10 years, and do you like the final outcome so much that you would spend all those years working on it? Remember that junipers thicken incredibly slowly, and you need at least 5 - 6 years just to double the current thickness (in the ground, under ideal conditions - not in a bonsai pot), and close to 10 years to triple it. (It would be an entirely different story with a deciduous tree, they can be thickened and re-shaped in a much shorter time.)
Also ask the following question: can I buy something that is only a couple of years away from my final image for a few dollars (or collect something)? This question is important because spending 5 - 10 years for a few bucks worth of tree is an incredible steep price to pay, no matter how much you enjoy bonsai. It's comparable to exchanging your car for a nice dinner.
However, it may also be that you enjoy this tree the way it is right now, and your final image is very close to what it is right now. Each of us have a different mental picture of how our ideal bonsai should look like. In that case, you should enjoy the tree and keep making small adjustments to it.
I am telling you this not because I have some hidden agenda about your tree, but because these are the exact questions I am asking myself lately. It took me a long time to get to this realization. At the beginning, I worked on everything I could lay my hands on. But then I realized that I would rather work on something that I can finish in my lifetime.
It is very hard to give advice with a tree like this, because we don't really know what is the owner trying to achieve. Some people are very happy with a thin little juniper with a few branches, others vision a final tree that could compete in any major show. Since we don't know what is your vision, giving advice is impossible. It is similar to asking help with building your house, but when you don't have any blueprint of the intended house: people don't know whether you are trying to build a hut or a palace, a fortress or a mountain cabin.
So, here is what I propose.
When people ask for suggestions, they should provide a general idea of what size, thickness, proportion, general shape they are envisioning. A simple 5-minute sketch is more than enough to give us an idea.
It is hard to give directions to someone who doesn't tell you where is he heading.
