It looks like far too gone now. Growing junipers indoors is a challenge and likely end up in failure like this. They need their winter dormancy or rest period and need to be outside in the cold but in a protected place. Second, they like to be dry especially when they are not growing. The water and fertilizer is not helping it at all and most likely rotting its roots.

If you have a place to move it outside to a unheated garage/shed that may arrest the problem but chances are slim at this point.