Sometimes you slice and print something which you would like to print again after a while. But you’re stuck with gcode and stl file and you haven’t no idea which parameters for slicing you chose. The object was great and you have no nerves to test many possibilities again. 
Is there any software which could retrieve this parameters from gcode file?
Depending on the slicer you use, you MAY find the appropriate parameters as comments in the header of the gcode file. Slic3r does this.
Pretty much all slicers do this; at the beginning of the .gcode file, it’ll list the calculations it made.
In case you’re not aware, gcode is ascii text. Just open it in a text editor and all well be revealed.
I know Cura has the option of importing settings from a gcode file, but as mentioned above, that might only be if the settings used are listed in the actual gcode file.