Look for the long, straight, sappy, leafy new shoots that have no flowers or fruit on them. They're the ones that will carry next year's crop. Don't cut them off. After the picking has finished you can cut away most of the shoots that have flowered this year, then train those new shoots along wires. The advantage of this is that the berries next year will be far easier to reach. That's a counsel of perfection. You could just leave the whole lot to do its own thing!