Q:

Years and years and years of Yishmael

Genesis 25:17 says:

וְאֵלֶּה שְׁנֵי חַיֵּי יִשְׁמָעֵאל מְאַת שָׁנָה וּשְׁלשִׁים שָׁנָה
  וְשֶׁבַע שָׁנִים וַיִּגְוַע וַיָּמָת וַיֵּאָסֶף אֶל עַמָּיו׃
And these are the years of the life of Ishmael: one hundred years and
  thirty years and seven years; and he expired and died and was gathered
  to his people.

What is the reason that the word “years” was written after every digit by Yishmael?
Rashi asks this question by Sarah (Genesis 23:1) and by Avraham ( Genesis 25:7) [lehavdil] but his answer in those cases doesn't seem likely to apply by Yishmael. 
By Yishmael - Rashi doesn't ask this question at all.
Is there a limud here by Yishmael? 

A:

The Maskil LeDavid explains that Rashi implicitly addresses the repetition of "Shana" by Yishmael (see here).
Rashi (Bereshit 25:7) says that the repetition of Shana by Avraham is coming to tell us that Avraham was as free of sin at 100 as he was at 5 years old. 
However, asks the Maskil LeDavid, according to some opinions, Avraham didn't recognize his Creator until he was 48 years old. If so, how can you say he was always free of sin?
Rather, Avraham did Teshuva out of love. The Talmud (Yoma 86A) says that when one does Teshuva out of love, his sins are uprooted, and considered as if they never happened. So Avraham was able to be considered as if he had never sinned because he did Teshuva out of Love.
Therefore, explains the Maskil LeDavid, once Rashi (Bereshit 25:9) explains that Yishmael did Teshuva, there is no need for him to explain what the repetition of Shana indicates by Yishmael. We understand that all of Yishmael's years were retroactively considered free of sin, since he did Teshuva.
So Rashi implicitly makes the same limud by Yishmael as he explicitly makes by Avraham. 

