When Electronic Arts Inc. releases the sequel to “Star Wars Battlefront” this fall, it plans to ditch one lucrative sales pipeline for another that is potentially even bigger, refined in mobile videogames.

Instead of selling regular “expansion packs”—the quests, maps and other content sold separately after launch—Electronic Arts will send customers free smaller packs more frequently, a way to keep them playing “Star Wars Battlefront II” indefinitely.

To...