From Omerta Wiki
Omerta undergoes resets on a regular basis now the rom-o-meter has been invented. What this basically does is let you, the player, vote if you think this version needs a reset or think it can go on for a while.
If this vote has an positive outcome and reset is likely to be followed, as per your requests. Another reason for Omerta to reset could be cause we have major changes to the gameplay / features for which we need an reset.