Cabbie, you are understandably annoyed by this girl saying "I'm like.." so frequently, and ask us why she can't speak properly.
I believe there are two different answers to this. The first being that she thinks she is speaking properly , because neither her parents nor her teachers have ever pointed out this irritating manerism and asked her to correct it.
We all have irritating habits, verbal or otherwise, and unless we are (made) aware of them will happily continue them.
The second reason for this sort of verbal trick is, in my opinion , that it is no longer considered polite or right to correct children too much. It is assumed that telling them flatly, as I was told at the age of six, to stop saying "dead nice" or "then I said" all the time does phsycological harm.
It may cause shyness or do serious harm, I suppose, but allowing this sort of annoying habit to go uncorrected often ends in people of all ages simply being dropped by their friends, and left wondering why on earth no-one seems to like them. This is harmful and hurtful too.
You can do one of two things here, either try not to be annoyed by this nice young woman's verbal tic, or mention how irritating this kind of thing is, perhaps using another expression as an example, then say, "I wonder if I have some similar unconcious habit that annoys people, and if so, if anyone would be willing to point it out to me".
This way, you are not directly correcting her, but discussing a common problem, which might make her aware of her own bad habit.