we have, at present, 130 plaques up in the city. Does it mean it could be more than 130 plaques?
"Up" is simply short for "put up", "placed up", "nailed up", "hung up", or various other ways of attaching things to surfaces (or otherwise displaying them). "Up" suggests that they are off the ground, and easily visible. Example:
She is a famous artist, with many of her paintings (hung) up in museums around the world.