Jesus did say we have to repent, but many misinterpret what "repent" means.
Luke 13:1 There were present at that season some that told him of the Galilaeans, whose blood Pilate had mingled with their sacrifices.
2 And Jesus answering said unto them, Suppose ye that these Galilaeans were sinners above all the Galilaeans, because they suffered such things?
3 I tell you, Nay: but, except ye repent, ye shall all likewise perish.
4 Or those eighteen, upon whom the tower in Siloam fell, and slew them, think ye that they were sinners above all men that dwelt in Jerusalem?
5 I tell you, Nay: but, except ye repent, ye shall all likewise perish.
Repent does not mean to stop sinning, because none of us ever completely stops sinning, even if we try.
The meaning of repent is shown by what I have underlined. These persons were under the false impression that because some men had been killed by Pilate, and because a wall had fallen on eighteen men, this was evidence that they were terrible sinners whom God punished. The Jews also believed this about those born blind, lame, or with other disabilities.
Jn 9:1 And as Jesus passed by, he saw a man which was blind from his birth.
2 And his disciples asked him, saying, Master, who did sin, this man, or his parents, that he was born blind?
We see here that the disciples supposed this man's blindness was caused by sin, either his parent's, or his own.
And it was the same in Luke 13. These persons supposed that these unfortunate persons who were killed were great sinners. They also supposed or assumed they were not great sinners because no such misfortune had occured to them.
This is when Jesus told them they must repent. They must realize this belief is false. Just because bad things happen to some people does not mean they are worse sinners than others. And just because no misfortune had happened to them does not mean they were righteous and held God's favor. They needed to realize that they too were sinners and in danger of perishing.
This is what repentance means, to turn from the false belief that we are righteous and know and believe we are sinners in danger of hell. Only when a man realizes he is lost will he come to Christ for forgiveness.