Here the 1837 edition accidentally replaced the preposition into with in. The 1908 RLDS edition restored the original into, as will the critical text. As discussed under Mosiah 23:26, the Book of Mormon text generally prefers the preposition into over in when referring to motion, especially across geographical boundaries. In expressions of the form “to go in(to) a land”, we never get in in the earliest text, only into (17 times, including here in Alma 47:1).
For another example of the change from into to in (and once more in the 1837 edition), see the nearby discussion under Alma 47:29.
Summary: Restore the preposition into in Alma 47:1: “and went up into the land of Nephi”; usage elsewhere in the text consistently supports into over in for the expression “to go in(to) a land”.