As others have said: I find 2CB pretty amenable to redosing, but it's generally close to impossible to 'boost' a weak trip to a significantly stronger one - redosing is most effective at extending the peak, not enhancing it. That said, a single large redose after a small initial dose seems to do the trick sometimes - e.g., a 20mg initial dose followed by a 50mg redose a few hours later might produce a second peak that is more intense than the first.
As with all psychedelics, though, I find that I really only have one shot to get to a really interesting or unusual headspace - if the initial dose doesn't get me there, I need at LEAST a good night's sleep before trying again and ideally at least a couple days of non-use. Redosing can produce a more intense body high, more active visuals, and to some extent more altered thought processes, but if I don't get to the point of ego dissolution / out-of-body experiences from the initial peak, I'm not getting there that trip, period. That said, 2CB doesn't tend to go to those really weird places mentally at any dose for me - if I want to get there, tryptamines or LSD seem to be the optimal route. Dosing LSD after 2CB rarely seems to get "weird," but DMT can still get me to breakthrough with little difficulty.