1)
Verses 4 and 8 already requested this! Why is this repeated?
1.
Rashi: In verse 4 is one Azkarah (mention of Hashem's name), and verse 8 has two. Here there are three - it is according to the strength of the Galus, affliction and redemption.
2.
Radak: Here it says "Ha'er Panecha", for verse 17 mentioned "mi'Ga'aras Panecha." (Also refer to 80:8:1:2.)
3.
Malbim: Now he prays for building the Beis ha'Mikdash, so he mentions with it Shem Havayah, which we mention only in the Mikdash.