もう

It is used when adding a quantity. Often, it can be replaced with 「 あと」(remaining...). However, 「 あと」 implies "this is the last remaining quantity," while 「 もう」 does not necessarily carry this meaning. When talking about the number of times, if it's difficult to consider it as the last time, then 「 あと」 is not used, and 「 もう」 is used instead.