If you can't store/feed bales of alfalfa, go ahead and try alfalfa pellets/cubes. If that doesn't work, add something else, but increasing forage first is always my go-to before adding concentrates.
You may need some trial & error to see what temperature, consistency & amount your horse prefers - my senior mare will only eat warm, just barely softened pellets and refuses to eat cubes at all. She'll also only eat 2lbs of soaked pellets at a time, and absolutely won't eat the leftovers later. My gelding will eat as much of whatever is offered no matter what, lol.
~Reserved Cash, 2011 AQHA gelding~
~Lark, 20-something Arabian mare~