Be aware that potted mint seems to use up the soil very quickly; mine has always died out from the center after 1-2 years. I think changing the entire subsoil would probably prevent that.

I use lemon balm in my sekanjabin, and also as strewing herb (it's supposed to make the heart glad). Apparently at one time, lemon balm was rubbed into furniture to polish it.

Maybe I will try to make some lemon balm syrup and see how that comes out.