If you were wondering, as I was, they do make a purely green veggie juice and it's good, real good: celery, spinach, broccoli, parsley, zucchini and/or cucumber, mint. I just finished my second large glass (450 ml for 4.50) with great pleasure and satisfaction. Asked for extra ginger in the second one: just great! And you might have guessed that it's called the Green Day. There's another mixed veggie juice with carrot, beet, red pepper, celery, fennel, etc, but everything else is fruit based.
It's not a place to hang out for long though because it's small and on a busy street. Also, as you probably know, juicing makes quite a lot of noise. I have my Bose QuietComfort15 and so I don't mind, but it's not really cosy. And in fact, of all the people that have come in since I got here, have ordered their juice and left with it in hand. Nonetheless, they have free wifi and places to sit.
Updated from previous review on Wednesday March 20, 2013
Here's an update: I came here every day before going to the university of astronomical observatory to get two big green juices. Today is my last day in Ljubljana and I had three as a final treat before going back to Madrid. I spoke with the owner and her partner for a while and they are super nice. Once more: definitely two thumbs up for this place.