"Uncrop" a drawing to restore part of a person?

[randomystick]

I have a digital drawing of a person whose top part of her hair + left shoulder is partially cut off, as shown:
https://imgur.com/a/5LIqPyc

How do I "uncrop" the image by making gimp restore the parts that got seemingly "cropped" off the picture?

I tried brute-forcing it by using the clone tool + heal tool, with limited success:
https://imgur.com/a/GeWlK0Q


Notes:
Heal Selection (from Synthesiser) doesn't work well, probably because it has nothing to sample from the top of the part I need restoring
Uncrop (from Synthesiser) doesn't work at all, it just adds a transparent border around my image

[rich2005]

Assuming that it is Gimp 2.10.6 rather than Gimp 2.6 (from a dozen years ago). One way is;

This might need more a bit of artistic license than a magic plugin.

Advise separating the subject from the background. I used the gmic plugin http://www.gmic.eu (oh-dear a magic plug-in  ) but there are other ways. (free-select tool, magic scissors, FG select tool..etc)  Accuracy not that important since eventually it gets planted back over the original.

Make a selection of what you think the top of the head contour is.

   

Use the Gimp 2.10.6 Warp tool, largish brush, click and drag to fill in the selection. Important the warp tool is easily undone, when complete select another tool to fix all the displacement.

   

With that over the original, looks like this. - oops forgot about the shoulder - same principle + a little shading with a fuzzy brush

   

[randomystick]

Thank you for the clear tutorial!