My approach would be copy and paste followed by cloning and healing.
Using rectangular select I would select using in this case rectangular select the area that needs fixing. Then switching to the move tool I would move the selection using Ctrl-Alt to the area just above. Then Ctrl C Z to copy and then return the selection to its original place then paste and then merge layers. Followed by healing.
Using rectangular select I would select using in this case rectangular select the area that needs fixing. Then switching to the move tool I would move the selection using Ctrl-Alt to the area just above. Then Ctrl C Z to copy and then return the selection to its original place then paste and then merge layers. Followed by healing.