wow...um don't just throw it out there is obviously new growth sprouting so it is not dead.something has happened to make the leaves dry up tho. it may be as simple as the tree taking a rest or maybe it was left to dry out too long.anyway do not water the soil unless it is dry,not having leaves will require a lot less water than normal, mist the tree daily. check at the leaf bases to see if there are new buds forming you may loose some branches but being a larger tree the chances of the whole thing being dead are a lot less than with a young tree. best of luck and keep us posted