@Laura White; I would recommend making a new topic next time as people usually don't revisit threads that have been answered. But to answer your question, there could be a few reasons why (ordered by most to least likely).
1) Are you making yourself known before you pass by her? Kicking is a defensive way to keep predators away from the lama, so if she doesn't know you're around she may perceive you as a predator when you 'suddenly' appear.
2) Are you touching her as you pass? Either by mistake or on purpose (some people train lamas this way to decrease their sensitivity to touch), touching a lama without them wanting to be could trigger them to defend themselves.
3) What's her past? If she's a rescue, she may have been abused or neglected, making her wary of all contact and have a larger personal bubble of space. If she was bought from someone, did she get any 1-on-1 time with anyone before being sold to you? Some people who plan on selling lamas sometimes will view the training as the next person's task and may only do the bare minimum with them (vaccination, trimming toes, shearing). If you've had her for her entire life, she may just be a bit cranky and that's her personality.
4) Where in life is she? Age-wise and herd-wise. Is she getting to the point where she's gonna be taunting the boys and flirting? Or does she already have a little cria (inside or beside). She may be protective). If not/too young/too old, is she top lama or on the bottom? Being on top may cause her to lash out at you to try and put you in your place.
5) She may have something stuck in/on her foot. The lady I got my start with llamas once found a small rock between the toes of one of her yearlings. They were much more cooperative once that was removed.
As to what to do with her: you may try the idea in #2 (touch them lightly and very quickly at feeding time). Just make it a routine and only a light tap (not a poke). You may halter her up and take her for a walk. Tie her up and work on lifting her feet. I'm really thinking it's just a space/sensitivity issue here. Go over in your head about what you are doing leading up to when she kicks, you may unknowingly moving an arm too fast, or talking too loud.
I hope this helps, and sorry for the wall of text.