Is this the big torsion spring which is falling out? (the one which looks like two coils with a "U" in the middle, and has a hook/straight part which fits into each side of the clutch pedal lever) If it's that one, have you tried compressing it a bit to make it fit more snugly? Is the clutch lever bent/angled or something, so that it's rotating the spring out of it's mounting points? (it might not be the spring which is the problem) Looking at the service manual, it doesn't look like there were any changes since 2010, so it should be the same design as in my '12 Legacy, and it hasn't had any issues like that)