He could have, and the meaning would have been the same. There is always more than one way of saying the same thing. Just because he said it one way, it doesn’t mean that he couldn’t have said it another way.She said, “No one, Lord.” And Jesus said, “I do not condemn you, either. Go. From now on do not sin any longer.” Jn 8:11.
If the definition of "repent" is "stop sinning," as you say, why didn't Jesus tell her, "Go, repent"?
You mean like in these verses:You really ought to learn what the word means.
21 And I gave her space to repent of her fornication; and she repented not.
20 And the rest of the men which were not killed by these plagues yet repented not of the works of their hands, that they should not worship devils, and idols of gold, and silver, and brass, and stone, and of wood: which neither can see, nor hear, nor walk:
21 Neither repented they of their murders, nor of their sorceries, nor of their fornication, nor of their thefts.
11 And blasphemed the God of heaven because of their pains and their sores, and repented not of their deeds.
You really need to learn your Bible a little bit better.