Here in the printer’s manuscript, Oliver Cowdery initially omitted the phrase unto you at the end of the verse. He later supplied it, probably when he proofed 𝓟 against 𝓞 (the level of ink flow is heavier). He made a similar correction in verse 1 (there the increase in level of ink flow is equally heavy):
The word years is clearly necessary in this context and was undoubtedly in 𝓞. (For discussion of when year(s) can be ellipted in a Book of Mormon sentence, see under Helaman 3:3.) Similarly, unto you was very likely in 𝓞 for Moroni 10:2. Either reading, with or without this phrase, is possible, so there would have been no motivation for Oliver to add the phrase here except that it was in 𝓞.
Summary: Maintain in Moroni 10:2 the corrected reading in 𝓟, “after that I have spoken a few words by way of exhortation unto you”.