Hi Marmaducky,

"I'm just wondering if anyone has any experience or knowledge about alternating the two?"

I have done both, but never really alternated them, preferring to water fast for as long of a stretch as possible without interruption.

"I'm thinking of doing 7 days water and then 7 days juicing (immaculately strained) and then water again, or some variation of this."

Unless you have specific needs that would require this, i believe leading in with juice, staying steady with water for as long as possible, then breaking with juice would bring the greatest benefits.  

"... I love juicing for how awesome it makes me feel, but juicing is a lot of work to do it right, as I only juice and strain what I will drink immediately."

Are you familiar with air tight jarring?  It is a way to do all of your juicing for the day at one time and keep the precious enzymes alive.  When i have done stretches of juice only and i was unable to stay near the juicer, this is what i have done.  

"Anyway, I wonder if the juice would have a recharging effect of sorts and I wonder how it would effect the next stage of water-only.  Might it make it easier or harder?  "

Interesting ideas.  It might have a nice recharging effect.  But you'd have to invest 2-3 extra days to get back into ketosis again, burn the extra muscle again making that transition, re-open hunger again and in interrupting the water fast, i believe that with two halves you would cleanse less deeply than one whole.  In terms of ease, it could go either way.  Harder in some ways and easier in others.  But overall, i suspect it would make it harder :).

"Or should I just stick to water until the end (not sure when that will be) and then do juicing after that?"

I believe this would be best :).