Advice on Restarting Jamie Eason's program

tbpmtb

i posted this on the general weight loss forum but I should have posted it here.
For those of you familiar with Jamie Eason's Livefit Program, how should I restart after a 2.5 week break?

I had just completed Phase 1 (and had not missed a day!) when I got sick and then I pulled my back. I am hoping to start again on Monday.

Do I restart at Week 1?
Do I maybe redo weeks 3 and 4, and build up any muscle that I may have lost?
Or do I just go straight to week 5 (or Phase 2, which includes cardio)?

I'm thinking about redoing 3&4...

Her whole point is to build muscle BEFORE introducing cardio. How much muscle have I lost in those 2.5 weeks?

Also I noticed a new program - "from Flat to All That". Should I start this one instead of Livefit? What's the difference?