i like the idea of an in-book arc recap (not necessarily by year).

more importantly, i like the idea of including a
"previously, on ___" in the first page or two of every issue.

spawn has a little paragraph in each (how else would you recap 100 identical issues?), and some other books have followed suit. the brief run of j.scott campbell's "danger girl" had an excellent recap at the start of each issue (typically one or two pages, complete with images!)

adding that seems like a relatively simple move, and would help readers catch up on pertinent back story, so that they dont opt to just "sit this arc out" simply because they missed an issue or two.