Replay Saints Row 3 Missions

How do I replay missions? For example: I’ve completed Act 3 but I noticed an achievement that you get if you complete act 1/2 in a different way. Thanks.

Anyone?

The Achievements are glitched mate i got lots of missing achievements ive got finish act 2 but ive not got act 1 ive finished the game but yet no act 3 achievement its all messed up

You can choose different ways to finish the act though, for example: (Act 2) Leave Killbane’s mask and get the ‘Apoca Fists’, or take is mask and get his mask. It allows you to replay the last mission of Act 3 but I would like to know if there is any way of replaying missions so I can finish Act 1 & 2 in different ways.