re-potting strawberry's

Morning all. I have strawberry's in hanging baskets and they are doing great , 2 of my hanging baskets have grass / corn and other  bits and bobs growing in amongst the strawberry's because i used to empty the old & used water that the chickens drink from which had small seeds ect in. when would you advise i can remove the strawberry's and repot in new clean compost , should i wait until the end of summer ?.
thank you .
John  

thanks for the advice & very much appreciated