Having taught us the Parshah of Korban Tamid in Tetzaveh (29:38-42), why does the Torah repeat it here?
1.
Ramban #1 (on Pasuk 2, citing Rashi): In Tetzaveh, the Torah is referring spcifically to the eight days of the Milu'im, and here, to future generations.
1
2.
Ramban #2 (on Pasuk 2): The Torah repeats it here in order to list it together with the other Morb'nos Musaf.
2
Ramban: And it is for the same reason that the Torah inserts briefly the Parshah of the Korban Pesach, even though it already discussed it in Shemos (chapter 12).