I've taken on many a "tremendous cables" project...and my mindset is always this: I focus on 1 row at a time, 1 repeat at a time...I don't look at THE END of the journery (being so far away)...but at the DAILY JOURNEY. I simply enjoy each row as it comes.
I think this aran sweater is worth your time and effort...and I commend you for starting over. It's exactly what I'd do...and have done many a time...and not because the project is eons old...because I've miscaluclated size, or gauge, or what have you.
I'm then grateful of the end result being something I'm proud to own, proud to wear...or proud to gift! I've knit many things for my kids and grands.
This aran you're working on is a real honey!