Last year (2017) I had a terrible strawberry year. My major problem was anthraxnose, but I had other plant issues as well. So I took the advice of our local garden center expert. This "expert" knows his stuff; he retired from teaching the Master Gardener class segment on Vegetable Gardening. His recommendation was to clear out 100% of the plants and plant debris and start fresh. In October 2018, I purchased and planted fresh plants, which the garden center said were grown in Canada. (Access to strawberry plants here is excellent as there are several nearby commercial growers in our area.)

My strawberry bed has 4 rows of 27 plants per row. The 2018 results were outstanding. From 108 plants, I harvested over 100 lbs of strawberries, making 2018 my best year ever. So my suggestion would be that you at least consider a fresh restart as one of your options.

Added note: About 15 years ago, our local commercial strawberry farms discontinued growing their plant runners for replanting. The problem was that the runner offspring plants were continuing to pass on plant diseases from parent plants. They now only grow certified plants purchased from out of state growers.