There is a similar request based on a special character: Clear Serial Monitor output field on receipt of control character · Issue #1726 · arduino/arduino-ide · GitHub. I know it's not exactly the same as what you suggested. And you're rightb that IDE 1.x indeed clears the serial monitor after a upload.
I could not immediately find your exact request so you can make a suggestion (feature request) on github (if you have a github account): https://github.com/arduino/arduino-ide/issues/new?assignees=&labels=type%3A+enhancement&projects=&template=feature-request.yml
And there is a request to implement a more full-fledged system: Serial Monitor plugin system to be able to add protocols like VT100, VTX, VTnnn, etc. · Issue #406 · arduino/arduino-ide · GitHub.