Border wall - is the plan to rebuild old sections?

I know that Trump is asking for $25 billion for a border wall with Mexico. But there is already a tall solid wall in some areas – I think a couple of hundred miles of it—and several hundred additional miles of barbed wire.

Of course, if they get the bucks, they’ll turn the barbed wire into a wall.

But is the plan to knock down the existing wall and replace it? Or is it to use what’s there?