Sounds like you have a second bar already? I always have spare bars for all my saws... no different than chains, sprockets, plugs, and filters.
If the Forester bar is not damaged and/or unrepairable, ie. still cutting straight, taking oil, and not damaging chain... then keep running it. No expiration date on bars, no different than chain.
Extra bars are nice to have so you can swap out during jobs if the one you're using gets damaged, and you can have a rotation in swapping bars on you saws, taking a few hours on an off day or night to dress all your bars for all saws.
Every night, one of my grandfathers would come home with a bucket full of chains and a few bars every now and then after a day's work. He'd grind chain and dress bars for his crew and himself for the next day. It kept production up, keeping his crew cutting all day being the goal.