Need g code for slicer to extend layer time

Hi. I am 3d printer and Im using slicer. The problem with slicer is that it keeps hotend all the time on object so it cant cool down.

Then on options I found "layer change g code" and an idea came to my mind. Is it possible to make g code that detects how much time next or previous layer used, if it used less time than 30 sec hotend would move away to make whole layer take 30 sec and then come back?

Right now I can only affect on minium layer time and speed, this however wont help be because now matter how low speed I set the hotend remains close to object and prevents it cooling.

The G-code available on 3D printers do not have the commands needed to do something like this.
However Slic3r options do give you some control over this. Filament Settings -> Cooling -> Slow down if layer print time is below: x seconds
It will not stop and let it cool but it will slow down the layer to be that minimum time.

Take a look at one of the many guides to 3D printer tuning such as:
Reprap development and further adventures in DIY 3D printing: Slic3r is Nicer - Part 1 - Settings and Extruder Calibration
Reprap development and further adventures in DIY 3D printing: Slic3r is Nicer - Part 2 - filament and printing
Reprap development and further adventures in DIY 3D printing: Slic3r is Nicer - Part 3 - How low can you go?