You could gently hand wash it and line dry instead of putting it in the washer & dryer.
I personally do not prewash any of my fabric and in 30+ years, I've not had a problem with shrinkage after it's been used in a quilt. The reason I don't is because not only do I not want to iron yards and yards of fabric, whenever I am forced into prewashing, I can't get out all the wrinkles.