I also am growing the new dwarf raspberry called Raspberry Shortcake, and from my experience the plant does stop producing in August. You should wait until spring when you see signs of new growth to fertilize this plant. Use a slow-release plant food like Osmocote. It is up to you if you want to prune off the long branches for a more tidy plant or allow them to grow long an tie them to supports for a more productive plant. I plan to keep mine pruned into a shrubby shape by trimming any really long branches. Keep growing, Marianne Binetti