Not sure if you are asking about reusing with the same image, or reusing a reclaimed screen to burn a new image. But either way, the answer is yes, screens can be reused repeatedly.
It's feasible that screens can last for years. It really all depends on the use and abuse you put them through.
Yeah I was concerned about using the actual screen again for use with a new image.
What would you say is the average life of a screen?
YMMV, but I have some screens that are 3 or 4 years old and have been reclaimed maybe 15 times or so. But then i have had others where I have gotten a hole in the screen after using only once. Screens take a lot of banging. the more careful you are with it the longer it will last.
What would you say is the average life of a screen?
It might sound pithy, but the average lifespan is "long enough". Irritating accidents notwithstanding, a screen will last long enough for you to get good use out of it, even as a hobbyist.
The key is to make sure the old image is truly out of the screen before you use it again.
Black images will show up when white ink images may not . . . but the old ink is still hidding in the corners of the mesh. That will block your next image if it's not out of there.
Get some de-hazer on hand - orange peel base is best. Cleaning your screens the same day rather than leaving ink set in them for days will help also.
Get a good light source where you clean-up so you can SEE what's left behind.
Newbie Question - Reusing Screens 
