When Jesus turned the water to wine, He asked the waiter to fill the jars up to the brim. Similarly, He intends to fill us up to the brim with His Spirit, and then to overflowing, so He can pour out of us into the world around us. When we are filled with the Holy Spirit, situations around us change, because He overflows. You might've been filled before, but why not be filled with the Spirit again? If Paul was filled more than once, surely we should be too!