הַמַּשְׂבִּ֣יַע בַּטּ֣וֹב עֶדְיֵ֑ךְ תִּתְחַדֵּ֖שׁ כַּנֶּ֣שֶׁר נְעוּרָֽיְכִי׃
yang mengenyangkan mulutmu dengan kebaikan, sehingga masa mudamu diperbarui seperti burung rajawali.
Rashi
that your youth renews itself like the eagle Like this eagle, which renews its wings and feathers from year to year. There is a Midrash Aggadah about a kind of eagle that returns to its youth when it becomes old.