In the first Bracha of Kriat Shema in the morning the phrase “ מחדש בכל יום תמיד מעשה בראשית ” appears at both the beginning and the end. Structurally, it seems that the essential part of the Bracha is the idea of the creation of light and dark. Praising God as the ongoing source of the existence and order of the world, and appreciating the benefits the world receives from the luminaries.
The Bracha begins and ends with this idea, however, in the middle there is an extensive tangent, describing the parts of the creation and how they are all involved in the praise of God. The highlight of this section is the description of the angels, and their unique praise expressed in the Kedusha.
We repeat the phrase “ מחדש בכל יום תמיד מעשה בראשית ” at the end, as a way to pick up where we left off before taking off on this tangent.
Support for this idea comes from Rav Saadiah Gaon, who held that the middle section was an addition for the tzibbur. But a person Davening by themselves immediately concludes the Bracha after the first “ מחדש בכל יום תמיד מעשה בראשית ” (i.e. the whole Bracha is about 3 lines long).
Perhaps he maintains that this entire middle section is the Kedusha and therefore an individual can’t say it. (An issue on which the Rambam’s position is unclear since in Hilchot Tefillah 7:17, he says that an individual cannot say this kedusha. But in Teshuva 313 and from the writing of his son, it seems that he changed his mind and allowed it – because one isn’t saying it as praise, rather referencing it as a description of the angels’ praise).