We were awarded phase 1 of a multi-phase project in AZ. If awarded later phases will we need to file new pre-liens?

Arizona's mechanics lien statute doesn't make any separate rules for different phases or stages of a project. So, sending one preliminary notice at the start of the job which covers the entire job should be sufficient. Of course, keep in mind that Arizona does have the 30% rule - so if the cost of the job jumps upward, it may be important to send the revised preliminary notice. More on that here: Arizona’s 30% Preliminary Notice Rule.

With that being said, if there are separate contracts for each phase of work, then it'd be wise to send notice for each separate contract to ensure that lien rights are preserved for the work being done pursuant to each agreement. 

For further discussion on AZ preliminary notices:

• Ultimate Guide to Arizona’s 20-Day Preliminary Notice
• Arizona Preliminary Notice FAQs