Most likely not. :( Mewtwo isn't really an event Pokemon as you can obtain it in HeartGold/SoulSilver and trade it to Black and White. It was really just a special Mewtwo tribute event kinda thing, the only thing special about it was that it had different attacks that it doesn't normally have. Most event Pokemon aren't released more than once or twice if they're event-only (aka Victini - although second time was a special event), but for Mewtwo where you can find it in-game, I doubt there will be another event. :x
Either way, you could always use the Quick Trade Thread to get a spare Mewtwo, otherwise just go back to past games and get a normal Mewtwo. For next time though, use Quick Questions to ask questions like this!