It depends on how much I enjoyed the game and (sometimes) how quickly I would be able to beat it.
For several Kirby games, I usually have a blast playing through them and they're relatively short, so yeah, I'll go back to them sometimes. This happened for some of the older Mario games, too, and that's helped a lot by the diversity of the levels and the ability to select different ones easily (especially in World). The optional ways to play a game also factors in to this. Mega Man: either shoot through them normally for a couple of hours or try mixing up the order for the bosses. Pokemon? Maybe test out some new monsters in-game to compare them with my progress the first time, or to trade some Pokemon or items I want onto my main game.
Other times, though, there might be one reason or another to not go back to it. Maybe I didn't enjoy it for some reason, or maybe it just takes really long to play through. Perhaps I just rented the game or played at a friend's house and don't own it. Or maybe I'm just lazy and don't feel like playing them, even if I tell myself that I should try it again sometime (i.e. Bowser's Inside Story, Link's Awakening).
