Conscious reinforcement helps. When you
notice you've slipped back into the old habit, then quietly say to yourself "Thank you for showing me this", and as soon as possible, re-revert to the "new" behaviour.
Also, while the paraliminals are excellent at helping you to change (and using them on and off over periods of weeks, or every so often after a month or two) will also boost your ability to retain the "new" behaviour, etc., until you get to the bottom of the reason
why you have the behaviour, you may need to continually reinforce - at some point the subconscious mind will either be completely reprogrammed, or it will "give up" the reason why (sometimes consciously, sometimes in a dream) you have adopted the behaviour.
Sometimes, also, there is a secondary gain for reverting to the old behaviour. An experienced hypnotist could help you with age regression back to the initial sensitizing event, and also pick up on secondary gain issues, and then use change-work to rewrite the programming involved. Then use of the paraliminals would help to reinforce new behaviours in an even more powerful way.
Cheers!
Unis