How often do you re-scape?

We started with a Marineland 5 gallon for our betta. Just some AquaNatural Biosubstrate, dwarf val, anubias, Salvinia. He’s done great, plants filled in, tank has kept great parameters, but 6 months in I’ve learned so much that I can do better. Since he’s our first fish, I’m learning as I go.

I’d like to start over, with better substrate and more wood/rocks. How stressful is it to move the fish? How do you cycle a tank if there’s already a fish? Can I just reuse the water with new substrate, additional plants and wood? Thanks!