Megan's prayer: Chris Tomlin's "My Glorious"

And all You ever do
Is change the old for new

Maybe it's because I've had a long day, or maybe it's just too late in the evening for my brain to fully function, but the above line has me stumped. What is the line in regards to? What is God changing from the old to new?  Why is that "all" He ever does?

I don't like to sing church songs that I don't believe in or don't understand what they are saying. Singing these words isn't just for fun, but it's a form of worship. How can I worship with this song if I don't understand some of the meaning?

I'm hoping some of my fellow bloggers can help me out here...