uninstalling and reinstalling TSB app (quoting pagl)

In a different thread, "pagl" (apparently a rep from Glu) said:

"Update to the most recent version of the game. Do not uninstall your game as you may lose your game progress."

First, how do you "update to the most recent version"?

Second, have any of you experienced what pagl cautions against, and lost your game progress?