I would remove old ripped piece or not, then sew a piece of leather folded around the front & back, then use a oblong punch & punch a slot in it.
Then I would sew around the oblong hole you punched thru it to reinforce it all.
It is fairly easy. But you cut 3/8" strips of leather.
Then start from the inside of your project with a long 3/8 strip of leather & go thru a slot, then up & over to next slot.
Then just keep repeating that order.