I recently bought a delicious Giardiniera and now that it's almost finished, would like to add more of the same vegetables. Is that O.K?
Yeah you can do that. I used pickled beet juice for hard boiled eggs as well :)
Yes, like Zombie says. Just keep it refrigerated.
Should have mentioned... doesn't always work too well with raw vegetables. You might need to steam the vegetables first. Read up a little on "quick" pickling.