Is it possible to attach the Android debugger of Android Studio again in order to check Break point after app has been closed ?
You may be able to attach a debugger if the app process is invisible but still alive. If a process is terminated or not is up to the Android OS.
However you will not be able to "check" a breakpoint as breakpoint only work if the code the breakpoint is contained is executed. Breakpoints therefore only work interactively - if you attach to a process after a breakpoint has been passed it is impossible to extract information regarding the process state (variables, ..) at the time the breakpoint was passed, because it is no longer available.