As far as I can see, the
lo is simply being used expressively to emphasize the speaker's point (and it refers to todo en la vida, as another answerer mentioned).
The meaning is almost the same as:
El dinero no es todo en la vida.
Money isn't everything in life.
lo gives a feeling similar to this English phrase:
Money - it's not everything in life.
Money is not everything in life.
That, or it could simply be a typo, assumed it's written. The writer may have started with El dinero no lo es and changed his/her mind but forgot to delete the
lo. This is admittedly a long shot, and I think my first suspicion is closer to the truth.