Having recently renewed both, I believe you can only renew MEP in the air, whereas first year you can indeed renew MEIR in the sim. Sim = a LOT cheaper than A/c.
MEP cost me nearly a grand to renew (had to go up twice due windshear on short finals and crosswind nearly at max demonstrated on first outting, which examiner thought would be a bit sporting whilst trying to demonstrate your asym landing!)
MEP - do it for fun, to keep your hand in, to remember that not all flying was about flying around with a blacked out cockpit, but I don't think it's REQUIRED for a job,...