Polyhouse cucumber

frnds i have grown cucumber rijkwaan multistar in 1000 sqm naturally ventilated polyhouse in soil.crops r 135 days old.yield so far 13.5 tonnes.i m  now termin ating the crop as there is heavy powdery mildew and mosaic virus infection.yield also dwindled to125-150kg per harvest which is not profitable for the amunt of nutrition we provide.i have following questions
1.is it necessary to destroy the old growbeds by ploughing the entire field raise new bed and apply base fertilisers and vermicompost as suggested by my consultant frnd or as my farmer frnd suggested i shall retain same beds for three to four crops just topping up the soil bed alone.which is better?
2.can i go for polycropping planting cucumbers and greens same bed simultaneously.