It depends on what kind of bedding you use. You don't need to replace the coroplast, it should last for a long time, I'm not sure on the exact number,or if there is one but it should last several years.
Using shaving (aspen, kiln dried pine, carefresh, etc) what I think most people do is use a dust pan and trash bag and scoop out the bedding, then use a spray solution of 1/2 water 1/2 vinegar to spray down the coroplast, then replace with new bedding.
What I do for fleece is, I roll it up, I take it outside I shake it like mad in the wind to get the hay off, then I toss it in the washer, while its getting washed I spray and wipe down the plastic (I don't use coroplast I use plastic 55gallon trash bags) with 1/2 water 1/2 vinigar solution and wait for the washer to be done, trasfer to dryer, wait for dryer to be done, and then replace in cage.
Its not that bad.
Have you seen
Cleaning or
https://www.guineapigcages.com/forum/bedding/21568-fleece-project-study.html ? They have other ways of cleaning, the 1st link of ways to clean with bedding, the 2nd link, about fleece as bedding.
