Hard water and scale does not directly reduce the life of the cell only how well it works. It's the corrosion of the cell from the acid cleaning that reduces it's life.

You may just need to focus on reducing the scale from the hard water. Replacing the water with lower calcium hardness water will help. Also, if your fill water is the same hardness as your pool, then one thing I found useful is to adjust the pool chemistry for hard water. This means operating at the low end of the PH (7.2) and alkalinity (80) ranges.