Those red leaves are dying and can be removed as they could be turning red due to a fungal infection, too much sun or lack of nutrients, most likely a lack of phosphorus in the soil. The word you used was "spotty" so this leads me to believe a fungal infection could be the cause and removing the infected leaves is the best way to help the plants fight off the infection. Strawberry plants continuously make new shoots or runners as the original mother plant is not long lived. Don't feel bad about ripping out the plants this winter or fall and starting with fresh plants in the spring. To discourage leaf fungus in the future try to water just the roots with a drip system rather than letting the foliage get wet. You can also try shading the beds during heat waves using stakes and a light sheet draped over the plants. Sun damaged leaves are more likely to suffer fungal diseases. Keep growing, Marianne Binetti