What is the meaning of "Hashem Aleihem Yichyu"?
Rashi citing Targum Yonasan: Hashem said that He will revive all the dead.
Rashi: This refers to the previous verse. All my years, You had mercy on them and said via a Navi that I will live.
Radak: The years allotted for a person, he can live longer if You want, like I will. The years allotted for me finished, and you added 15 years to them!
Malbim: After I despaired, Hashem said that those years, I will live.
What is the meaning of "ul'Chol Bahen Chayei Ruchi"?
Rashi #1: Before all the Mesim [that Hashem will revive], he revived the life of my Ru'ach.
Rashi #2: Everything on which the life of my soul depends, Hashem said that they will live (Malbim - He will prepare them).
Radak: I will tell everyone that my Ru'ach is living in these extra years.
Why did he say "v'Sachalimeni v'Hachayeni"?
Rashi: Now I know that You will heal me and make me live. You will heal and strengthen me. This is like "Yachlemu Veneihem" (Iyov 39:4).
Radak: Both of these mean 'heal me.' I supplicate that in the years that you added to me, I will be healthy.
Malbim: You made it as if I had a dream that I am going to die, and Hashem revived me.