Posted: 06/08/2017 at 15:20
You can cut some of the older stems right back to the base which will promote strong new shoots from below ground or low down on existing stems. Don't cut any of the shoots which have grown this year as it is those which will bear the flowers and fruit next year. Also remove any spindly shoots at the base and the twiggy bits which bore the fruit this year.
However, don't do any of this until the bush goes dormant - prune it during winter. RHS advice here: