For Forms you get later, there is a quicker way to refill up the Drive Gauge. First, once the Drive Gauge fills up, do a Drive as usual. Before the Drive Gauge goes to empty, use a save point to exit out to the WorldMap. Come back and your Drive Gauge should be back to Max.

For a second way, it is with Olympus Coliseum later on. Enter and Exit out one of the Tournaments, your Drive Gauge will also be Max, regardless what you had.

That means if you have an empty Drive Gauge, you can fill it up to Max with the second way. Remember, later on, Summonings also require Drive Gauge and that means this is pretty handy.