Just yesterday I wrote at length regarding how surprise onside kicks would best be handled in Madden 12. The simplest, though not necessarily most ideal solution, would be to limit it to one attempt per game. Teams don’t attempt surprise onside kicks more than once because the opposition is much more aware of the possibility and the risk-reward ratio is not nearly as enticing with field position being so valuable.
In an interview with ESPN today Ian Cummings has stated that the limit, which was at first set to allow for up to two attempts per game, has now been changed to a single attempt. It remains something that will be looked at and could be changed even in tuner sets but for now that seems to be the best way to proceed with the feature.