What is be sought?
Rashi: The dispersed of Yisrael - "Es ha'Ovedes Avakesh" (Yechezkel 34:16).
Metzudas David: What was lost.
What does one make perish?
Rashi: Yisrael in Galus - "va'Avadtem ba'Goyim" (Vayikra 26:38).
Ibn Ezra: The same matter that he sought.
Metzudas David: He overtly destroys what had been lost.
What should be guarded?
Rashi: Yisrael - "Yevarechecha Hashem v'Yishmerecha" (Bamidbar 6:24). This is when Yisrael do His will.
Metzudas David: Something that should not be open for anyone to take it.
Verse 5 already mentioned "Lehashlich"?
Rav Sadya Gaon: There, it means to abandon. Here, it means to throw.
Rashi: (Above discussed Bachurim.) Here discusses all of Yisrael - "va'Yashlichem El Eretz Acheres" (Devarim 29:27).
Ibn Ezra: Here discusses casting off what he guarded.
Metzudas David: Here discusses casting it to a Hefker place, where anyone can take it.