Repentance is accepted up until before death

from the Prophet ﷺ who said, "Indeed Allah accepts the repentance of a slave until he gurgles (takes the last breath)."

عَنِ النَّبِيِّ ﷺ قَالَ «إِنَّ اللَّهَ يَقْبَلُ تَوْبَةَ الْعَبْدِ مَا لَمْ يُغَرْغِرْ».