PowerPro Spectra
 

Anyone know how long this stuff last? I've had some for a few years(2-4) now and am wondering if I should replace it.

6-7yrs or so

It depends on how much the line gets used, very hard to put a time frame on it. Dont worry about the line that never or seldom leaves the reel but keep an eye for wear on the line that is constantly going through the guides. A little fraying is going to happen but when you see a section that looks excessive get rid of it. As you slowly lose line to the point where its level on the spool is getting low just take the line off the reel add some backing and respool to the level you like. If you have a longer length of worn line, say 100yds, reverse the line so the fresh line that was on the bottom is now on the top. Generally I get 3-4yrs of almost weekly use before I reverse the line but I occasionally remove short pieces that show the most wear.

I've known people that after a year or two will off load it from one reel to another to in a way flip flop the line so that the unused line now can be used. I've had the same spectra on 2 of my reels for 3 years now without any issues.

Sounds like its time for the old flip-a-roo.