How To: App2 kills App1, then App2 continues on

Here's my situation

App1.exe is running. If user clicks on a button then App1.exe will Shell App2.exe. App2.exe kills App1.exe. After App1.exe has stopped running then App2.exe deletes its EXE name from the folder. Then App2.exe with take temp.exe and rename it to App1.exe (which will be a new version of App1) then App2.exe shells App1.exe then App2.exe closes itself out.

How to do this

Note: Both App1 and App2 are my programs.