Then is literally “Then after this” (see Revised Standard Version). New English Bible has “After this.”

The expression Let us go back to Judea must not be understood in the sense of asking permission. Technically this is a “hortatory” expression, but there is certainly no exhortation involved. It is a kind of polite command in the first person plural. The equivalent in some languages is “We must now go back to Judea” or “We should now go back to Judea.”

Quoted with permission from Newman, Barclay M. and Nida, Eugene A. A Handbook on the Gospel of John. (UBS Handbook Series). New York: UBS, 1980. For this and other handbooks for translators see here .