I would probably start a new character with a new world just because progression with an old character in a new world or a new character in an old world is probably more disorienting. Like you would have recipes but not the stations to use them, or you would have the stations but not the recipes.

Most of the new content since early access began is loaded to the mid and current late game. Since you already have an old character and an old world you are in a flexible spot. You could also tailor your own compromise by using your old character to drop or build some basic stuff in a new world so that your new character can move the early game along faster, but practice some restraint.

My personal opinion is that the swamps is where the game really begins to shine and it is from that point onward that most of the new content begins to appear.

You can still find the new content in an old world but it depends on how much of your world has yet to ever be generated. New additions to the world-gen will not appear in previously generated areas.