it really depends more on your brightness target than anything, but once a CCFL goes, there's nothing you can do but replace it.
18,000 hours is about two straight years of 24hr operation-- i'd imagine most people have had to replace fluorescent lightbulbs when dealing with a similar timeframe.
One thing to try is: leave the monitor on for 30 mins to warm up, set Display Cal to 6500k (or whatever your desired white point) then start the calibration to get to the pre-calibration routine where you dial in the white point using the manual monitor controls. Set the brightness all the way up, then adjust the RGB gains until you hit the target. You're probably gonna end up with something like 100% blue, and you're gonna have to keep going down down down on the other two until the monitor becomes pretty dim. If you can then actually hit the target, make a note of the brightness level-- that's your monitor's new maximum output.