vivace comes form vita. So literally this means "there is more life in it now".
About people vivace is a nice way of saying they are hyperactive or they talk all the time, an has a connotation of appreciation to it.
About activities it means something is full of energy, interesting, ever-changing.
Can also be used ironically to mean someone or something is too much of the said attributes.
This is typically use by teachers of small children to say they're too loud when speaking to their parents or other people with whom they must use tact to speak about the children (the school's principal etc.)
Hope it helped
This might help (or not): http://forum.wordreference.com/threads/ora-adesso.9473/