When you need to replace multiple text in illustrator right now you need to copy the text go to Edit - Find and replace, paste your text, replace it, and then click done which results to closing the window.

So you must reopen the window every time for the next replacement.

You can have this option as it is in InDesign where you can copy and paste text while the window is open and the window stays open after you done replacing. Also it will be more convenient to be able to add the panel at the dock.