The 1858 Wright edition dropped the modal verb will here in Alma 19:36, but the first RLDS edition (1874), following the 1840 edition, restored the will to the RLDS text. Either reading, with or without the will, works in this context, as exemplified elsewhere in the text:
In each case the critical text will follow the earliest textual sources; thus here in Alma 19:36 we have “to all people who will repent and believe on his name”.
Summary: In accord with the earliest textual sources, maintain the auxiliary verb will in Alma 19:36: “to all people who will repent and believe on his name”.