Here "went up" is probably a reference to going north. Say that he departed in the most natural way for your language. AT: "Isaac left there and went to Beersheba"
"for my servant Abraham" or you can make the full meaning explicit. AT: "because I promised my servant Abraham that I would do this" (See: [[rc://en/ta/man/translate/figs-explicit]])
You can make explicit why Isaac built an altar. AT: "Isaac built an altar there to sacrifice to Yahweh" (See: [[rc://en/ta/man/translate/figs-explicit]])
To "call on" means to pray or to worship. Here "name" stands for Yahweh. AT: "prayed to Yahweh" or "worshiped Yahweh" (See: [[rc://en/ta/man/translate/figs-metonymy]])