I have a cousin who has told me that after the last day of the current Jubilee that the opportunity for repentance will be over. Is this true?
No. As long as the world exists then God will forgive the repentant.
When the world will end no man knows the date (Matthew 24:36; Mark 13:32).
“If anyone says to you then, ‘Look, here is the Messiah!’ or, ‘There he is!’ do not believe it.” (Matthew 24:23)