What should you do if you have a boyfriend who has lied to you several times before and you catch him every time and just recently caught him in another lie two days ago?

There are two sides (at least) to every story. Did he really lie, or do you just THINK he lied? If he DID lie, then you need to ask yourself why you continue to put up with him. Are you that needy? Respect yourself. On the other hand, if he did not "lie," but made some honest mistakes, perhaps you're being over-critical, in which case you need to make some attitude adjustments.