First off, Rachelle Lefevre seems to have gotten over being dropped from the Eclipse cast. Her recent interview reveals that she's glad her fans sent their love and affection and deep admiration for her prowling around after Bella in the forest, and that she hopes most of the scenes she filmed for New Moon make it to the final cut.
It was recently revealed that Rachelle Lefevre, who played the notorious vampire Victoria in Twilight, will be replaced by Bryce Dallas Howard in the third film in the franchise, Eclipse. This comes as a surprise to many, possibly including Lefevre herself. She did choose to take a role in another film, independent movie Barney's Version, and according to producers, failed to alert them in advance that she would be in this other film. Apparently it means she will not be able to take part in pertinent rehearsal and photography time for Eclipse, and thus was eliminated from the cast and swiftly replaced. However, Lefevre has decided that the most logical response to her replacement would be to take legal action for breach of contract. In other words, she wants them to pay her for Eclipse anyway. The producers and other bigwigs in the Twilight film franchise believe that she is not owed anything because she should not have taken any other (albeit less major) roles while working on the Twilight films, though Lefevre of course disagrees. Some sources do assert that pataking in other roles was allowed in her contract, but there is contention on this matter.