Redosing passed 2 hours does nothing for me.. Now I plan to just take more on the first dose and redose a small amount to lengthen after about an hour.. Last couple rolls i tried redosing more (amount + times) or later on in the roll and it did nothing for me.
I'm lucky enough not to suffer comedowns, so the aftermath was the same, but i believe redosing is more harmfull so i won't be doing that again..
From what i have been able to read on bluelight there are plenty of people who do have succes redosing, so i guess the only way to know for sure is try out a couple dosing strategies and see for yourself (taking appropriate breaks in between ofcourse)