I was talking with my neighbor the other day about fishing. He asked how often he should spool new line onto his reels. The hard-core elite series Bassmaster classic voice within me almost churned out "every tournament day". The amateur, day-job weekend angler inside of me said "It depends".
At least once a season should be the minimal, even if it's on your kids Zebco. Lines get nicks, abrasions, slices&sediment all over them from just sitting in the garage.
I would suggest a line conditioner to prolong the lines life&improve casting. I recommend relining when you need to. If large memory loops will not work themselves out with conditioner and your just not feeling a bite. I would change the line.
Whether it is a trophy fish or a trophy adventure with your kids you don't want to lose a fish because of bad line.
Good luck !