Rashi on Numbers 6:12/רש"י על במדבר ו׳:י״ב

1'והדר לה את ימי נזרו AND HE SHALL CONSECRATE IN HONOUR OF THE LORD THE DAYS OF HIS NAZARITEHOOD — i.e., he shall again count the days of his Nazaritehood as though for the first time (i.e., he must begin the counting of the period of his Nazaritehood from the first day, not resume it at the point where it was broken off).

2והימים הראשנים יפלו AND THE DAYS THAT WERE BEFORE SHALL BE LOST — i.e. shall not come into account.