If your question is about how you could chane a station into a rich one, i guess there is no way it would happen on its own with any amount of player intervention, not without FD intervening directly. You could propose a CG though. Why this station is a rich one or not currently is unclear. I think many of these are chosen by FD (and some PG?) from the start. One has to remember than there can be both interior types in a single system with the same faction in control, and as far as i know, i never saw any station change.