The easiest solution is to give the AI the ability to see player's numbers.
When it knows exactly how many 2s on the table, it can't lose. So all you need to do is to add some randomness to its decisions.
Say, a 30% chance of bluffing, 20% chance of saying "lie" when the wager is actually correct etc.
It won't be the smartest AI, but many players probably won't notice that it's cheating.