I had this problem with my original 2010 iPad and if I left it completely shutdown for 3-4 days the issue wluld not return for about 2 months, or so, where I would have to shut it down for another 3-4 days.
The screen ghosting never just came back within a couple of hours.
There is obviously a more complicated screen problem/issue going on here, if the screen ghosting is returning so quickly.
I have to agree with Lotus Pilot.
The out of warranty cost to repair/replace this with another iPad Air 2. will be nearly the costs of a new 2018, 6th gen 9.7 inch iPad with much better and faster specs and now have Apple Pencil support.
If this screen ghosting really bothers you, I think it would be better to consider a purchase of a new or Apple refurbished iPad at this time.
You can get an Apple refurbished, 32 GBs, 6th gen, 9.7 inch screen iPad for $279 right now.
An Apple refurbed 128 GBs model 6th gen 9.7 inch screen iPad is well under $400, right now, too!
Refurbished iPad - Apple
This is the time of year to get a new iPad.
Good Luck to You!