The answer to your question is that it is not the same for everyone, but there are some general guidelines as follows:
1) Fruit and veggie juice is loaded with vitamins. Literally. The exception is B12. You should take a B12 supplement. Also zinc, and vitamin D if you want to. It probably would not hurt to take a multi-vitiman, but it's questionable if it is needed. I would not take megadoses of any vitamin at all while juicing.
2) Juicing does not give us enough protein. Period. Because of this, eventually we will experience symptoms of protein defficiency. How long this takes and how severe differs from person to person, many of us can juice for 60 days and not have any problems at all. To be safe, we should take a protein supplement while juicing, especially if juicing for more than 15 days. I think the recommended amount is 20mg of protein. There are several good protein supplements available, and while some are horribly over priced, others are reasonable. I use Nutrasumma Pea Protein, it is gluten free, non gmo, no flavorings added, no sweeteners. The taste isn't bad - some protein supplements are truly nasty tasting. I got it at Sprouts, but any good health food store should have the equivalent. I think I paid about $20 or so.
3) Juicing does not give us enough fat/oil, and we need some to live. Ironically, when we burn fat, we do not get any fat/oil released into our system, so we need to take a small amount of oil daily. One teaspoon is enough, and you can use any type you like. I usually use olive oil, just add a teaspoon to your juice, you will never know it is there.
I can't drink coconut water, I have lived where coconuts grow, and what comes out of a coconut is very different from the nasty stuff in cans. Eww! So I put a pinch of salt in one of my juices every day. I like pink Himalaya salt, but really any salt will do.
A reboot is not one of these extreme fad diets where we deprive ourselves and run the risk of deficiencies of this or that. It is designed to give us *everything* we need to remain healthy while our bodies burn fat, and we can do it for a couple of months if we want so long as we have fat to burn.