Have you heard of ICOs with multiple rounds? Like they raise a certain amount of money now, use that money for primary aims and goals, and then a few months/years down the line (as part of their original plan) launch a second round to fund additional goals and further project development? Just wondering if this is a thing, if so please provide me with some links to projects that have done so.
Yes, it is pretty normal. They offer cheap tokens at the beginning and gradually increase the price of the token in each round (to attract early investors). 
i think all ICO project always have a fixed rate,
but they will give different bonus for each round, thats why an ICO project will run a multiple stage on ICO