Which tradescantia is it?

Hi, welcome to G oY, I am assuming you mean the hardy Tradescantia, you can divide this in autumn or spring, the choice is yours, Derek.

The perennial ones do tend to look very sorry for themselves this time of year once they've done their thing, I've just cut mine right back as they were flopping everywhere and yellowing, they'll be back next year no problem, sometimes they will produce a bit of fresh new growth this year.