Matt 27:3 Then Judas, His betrayer, seeing that He had been condemned, was remorseful and brought back the thirty pieces of silver to the chief priests and elders,

If you read the KJV, the word remorseful says “repented himself”, which, on the surface, indicates a change.
The word used is not the same as in Peter’s sermon on Pentecost where he said, “Repent, and let every one of you be baptized in the name of Jesus Christ for the remission of sins.”
Judas simply regretted his actions, while Peter asked the audience to think differently and change their behavior.
Anyone can regret an action, but what are you going to do afterward?
Judas hanged himself.
After his denial, Peter cried.
Although it never says, “Peter repented”, he thought differently and changed his behavior, which is the definition of repentance.
Peter stayed around.
He went to the empty tomb.
He met Jesus on the seashore.
He was in the upper room when the Holy Spirit filled them all.
He preached the message of Pentecost.
Follow Peter’s example and repent – think differently and change your behavior (in Christ).