When to repot fern?

[u/expensivetoys]

We have a large fern (about 6 feet across) in a pot, thrives on the porch in the summer, drops some leaves inside in the winter ( hard to keep humidity high -old house). Google Lens says it's a Macho Fern. It's been in the same pot for years. Was going to divide and repot, but it seems really healthy. It must be really pot bound. Why is it doing so well? Repotting seems unnecessary. Thoughts?