I didn't think it was necessary to move every year, but I do believe you should move them after a couple of years to prevent build up of lurgies and diseases.
Aha, here you go, taken from the HDRA site, yup, you need to include them in your crop rotation.
Organic strawberry production is considered relatively easy in comparison to top fruit. Weed problems can be overcome by mulching with black plastic and straw. Systems of mechanical weeding are being developed to reduce the use of polythene. There are relatively few problems with nutrition, pests and diseases. Grey mould (Botrytis cinerea) is the most common disease and to a lesser extent powdery mildew (Sphaerotheca macularis). Crop rotation is essential to prevent the build up of soil borne diseases but diversification into other crops would be required to achieve this. Adopting this practice requires a major shift in approach for an existing conventional, outdoor strawberry unit. The recommended four year break in strawberry production means that only 20% of the land can be replanted with strawberries each year. Slugs can be a problem in wet areas and can be encouraged by the mulches used for weed control. Pests such as aphids, strawberry blossom weevil and spider mite do not often pose problems for existing organic growers. A possible explanation is that insect predators and parasites are encouraged by habitats such as hedgerows and the almost complete absence of pesticide use on organic units at present
