FrankField - Yes there are scheduled promos that I seem to see that never misses. For Example Holidays. I am very sure that there will be a promo on Christmas since Scirra doesn't miss out on christmas holiday promos but that is very far off.
But there are also other big holidays that Scirra might offer one but it is unsure. It depends on Scirra if they want to make the promo like this Easter, there were no promos made by Scirra but unexpected events might give them the decision to make a promo this year. For Example a new game jam.
Just keep checking on Scirra Store.