Well worth giving the screen and wiper blades a good clean, certainly get a glass polish (I use the Gtechniq version). I also use the water repellent from Gtechiq as lasts up to 18 months against say 3 months for Rainex.
I have to say though, the water repellent does mean the blades stick when not used for a while when first applied, does wear off though and keeps the screen really clear.
Andy