IF she's a pathological liar it won't register in her brain, one that she's been lieing, and two, that you know. In other words either she'll ignore what you said as if she didn't hear you or she'll deny ever saying that.
We had a pathological liar, we didn't know at the time that she was, and we called her lie-face. I was friends with her first and the first lie she ever told me was that she was Nick Carter's cousin. Yes, the Nick from backstreet boys. I figured, at the time, "Hey, someone must be related to him." She took the lie as far as to calling him on a pay phone when I was around. My best friends didn't believe her from day one that she was telling the truth. So later on she tells me that her mom had won the lottery and her family had over a million dollars, however they were trying to save the money and so they never spent it. That was when I was like... "Hmm, not so believable." The last one that really pushed me over the edge was when she said that Shania Twain was her aunt. This happened at a sleepover that both of my best friends were at too, we then busted a gut laughing our asses off.
Over the years she's had 5 grandmothers die when school projects were due and I think 4 grandfathers died.
We ignore her now.