So you re-bled them recently? That second post of yours provided much more information than the first, and changes things. If it continually got softer+ loss of fluid, then there is a leak. When the level falls too low in the resevoir it pulls air in. You need to re-bleed them if you havent since your brake change. Look around for where you have fluid coming out. check your lines at the master cylinder, and the bleed nipples at each caliper.