Just completed my first 2 years as an Allotmenteer so of course I am now an Expert in All Things Lottie !
I inherited a patch of rough ground with just strawberries so I put them all in one 14 x 4 foot bed and got loads in both summers
Tried it with a fleece and then a lot of straw which worked best
Some experts say the plants are only good for 2 years and then replace or use their runners
I think that the suggestion by NE & SF is a good one as the plants must have taken some of the nutrients from the soil and its difficult to dig / hoe / manure with permanent plants in situ
Got this quote from a National Institutions site
"Strawberry plants can produce fruit for five or six years. However, after the first two years the yields will be reduced dramatically and a build-up of pests and diseases can occur. Strawberry beds are usually kept for two or three years before they're cleared and planted on new ground."
I think I will dig up and rotate which sounds like a West Country dance.
Good luck Ivyhouse and let us know how you get on