I would cut it back. My Foxgloves are already cut way back, and I pulled out the real ratty-looking ones. I kept a few smaller seedheads to collect some seed. Some plants will come back for 3rd year, especially if they don't exhaust themselves going to seed, but I start them from seed every year to be sure to have nice blooms in the Spring.

Once the tall seedheads get to the end of blooming they don't look good anymore and I would cut them back even earlier if it weren't for the fact that the bumblebees just love the flowers.

Thank you. Now the next question is how far do I cut it back, or is that more of a personal preference?

Nevermind. I cut it down to just before the top of the blooming shoot is.