I think it helps to look at two different commentaries on this verse. First we'll reproduce the Greek, and then the commentaries on the Greek.
εἶπεν δὲ αὐτῷ ὁ θεός Ἄφρων, ταύτῃ τῇ νυκτὶ τὴν ψυχήν σου αἰτοῦσιν ἀπὸ σοῦ· ἃ δὲ ἡτοίμασας, τίνι ἔσται;
Westcott and Hort 1881
The first commentator is A.T. Robertson.
Thou foolish one (aprwn). Fool, for lack of sense (a privative and prhn, sense) as in Luke 11:40 ; 2 Corinthians 11:19 . Old word, used by Socrates in Xenophon. Nominative form as vocative. Is thy soul required of thee (thn psuchn sou aitousin apo sou). Plural active present, not passive: "They are demanding thy soul from thee." The impersonal plural (aitousin) is common enough ( Luke 6:38 ; Luke 12:11 ; Luke 16:9 ; Luke 23:31 ). The rabbis used "they" to avoid saying "God."
Robertson's Word Pictures of the New Testament
The second is Henry Alford.
αἰτοῦσιν, not strictly impersonal; there are those whose business it is, even the angels, the ministers of the divine purposes: see ch. Luke 6:38 and note. The merely impersonal sense may be defended: cf. Luke 12:48 : but this saying seems so solemn, as to require something more.
Henry Alford's Commentaries on Luke 12
The two commentators agree that the verb αἰτοῦσιν could be a case of the impersonal third person plural. Robertson gives a good description of this idiom. He notes that it has at least a few other occurrences in Luke. He claims that it allows the author to avoid having to say "God", in the same way that the passive would, but keeping the active voice.
This is one possible answer. That the Greek verb αἰτοῦσιν is impersonal, and thus the Vulgate's choice of repetunt is a way of copying the idiom into Latin. But Alford allows that it could be otherwise, explaining that it could possibly refer to angels. For this reason, I hesitate to say definitively whether repetunt is impersonal. I think it's a matter of interpretation.
It's also worth mentioning how the Douay-Rheims bible, an early and more literal translation of the Vulgate, keeps the third person and the active voice.
And I will say to my soul: Soul, thou hast much goods laid up for many years take thy rest; eat, drink, make good cheer.
But God said to him: Thou fool, this night do they require thy soul of thee: and whose shall those things be which thou hast provided?
Luke 12:19-20 Douay-Rheims