These are some resources I have used to keep my skills up, push them a little and to migrate from the classical genres. Some of them include audio content which is great too. I have listed Amazon links as you can mostly peak inside the books there (and they might send me a $1 one day for listing them here)
DISCOVERING ROCK VIOLIN INTRO TO ROCK STYLE TECHNIQUES AND IMPROVISATION BOOK/CD This is a formidable book that takes you right through the transition into play many genres (most modern genres have similar roots), pentatonic, chord structures etc.. lots of play along stuff. It won’t transform you over night, but you will discover what you don’t know and how to know it (with lots of work)
Rockin’ Strings: Violin: Improv Lessons & Tips for the Contemporary Player – Bk/Online Audio This is a play along violin book to dip your tow into the Rock genre with rock violins Mark Wood. It was a bit light on for me, but might work for you
The Jazz Violin and Harmony Handbook This little book gets very technical very quickly without a lot of explanation, but outlines a process to practice…warning you have to do the heavy ligfting yourself…but hey thats the deal anyway