Icon question

I've researched through the memories and can't find one that adresses my question. Here's the problem: Let's say I already finished an icon, saved it and closed the whole thing (meaning the program). Then after a few hours I realized I made an error in the icon that I want to change. For example, there's a text that was mispelled or I want the text removed from the icon. Is there any way that when you pull up the finished icon, to disect, meaning have the icon with seperate layers again? I mean, I know people would say to just go ahead and recreate it but sometimes its hard to achieve the same effect in either coloring or brushes etc.

Thanks in advance for the help!