1989 560SEL, 143000 miles

I need to replace the high-pressure hose of my A/C system (it has some cuts). The car has been without refrigerant for over a year now. I did not own the car when it lost the refrigerant. While I'm under the dash should a go ahead and replace the expansion valve anyway? I know that the valve is cheap but it looks like I'll have to buy some crowfoot wrenches for the task.

I'm undecided which way to go. Can anybody give me a convincing reason one way or the other?
~Dave