I've been thinking about picking up some of the DLC packs, and I was wondering if the DLC is repeatable or whether it's restricted to one run per save file. For example, I do an early run of the easy EXP map/battle/thing. Can I do another run later in the game when I pick up some new units?
Yup, all DLC maps can be replayed as often as you like.
Likewise, Spotpass teams may be summoned and fought as many times as desired.