You can extend the life and comfort of safety shoes with replacement insoles. Most insoles of shoes are removable and can be taken out easily.
Once your safety shoes are worn for 6 months or more you probably have compacted and wore down the original insoles in your boots. You can restore comfort and support to the shoe or boot with purchasing new insoles.
There are a large number of replacement type insoles on the market. Most offer additional arch support and added cushioning. Spenco is a good choice and makes a number of different insoles.