Hi Long Final,
You require the same as any other FAA pilot does... a BFR.
This is every two years and is a flight of an hours duration going over maneouvers of *your* choice together with an hours worth of ground school. The instructor has to endorse your logbook to say this has been completed.
However any FAA checkride such as an IR or Multi checkride counts as a BFR.
Other than that you need to keep your IR current by the required approaches, holds etc within 6 months / 12 months or an IPC.
Plus the 3 take offs and landings within 90 days to carry passengers (paying or non-paying).
Best wishes,
Charlie Zulu.