I've never canned juice before, but it should be fine to can it using the guidelines for canning the vegetable you're juicing. High-acid foods like tomatoes and fruit can be water bath canned, but low acid foods like beans and other veggies need to be pressure canned. It's easy once you try it out, and it's a great feeling seeing your pantry fill up with shelf stable food you made yourself.
I know this thread isn't about juicing, but... why? I've never understood the juicing thing. By juicing something you're removing all the fiber and a lot of other good things. Your body needs that fiber. Smoothies are a more complete meal than juice.
I juice when I'm in one location for more than a few weeks.
I started doing it to juice beets to naturally lower my BP, and it works!!
Never considered canning beet juice though, but I like the idea. I'll prolly start BP meds shortly due to the ease of use, but if SHTF, canned beet juice may literally be a lifesaver....