Hate to say but cannot remember replacing mine yet (10 years). I do cut off 10 ft each year and retie all knots and replace swivels and snubbers. I think life expectancy depends on how much you use, how rough you are, how deep and what weight ball. I use 200 lb Tuff Line braid only use 13 lb gibbs pancake weights and have looked after line, store out of sun and wash after each trip. Do have spare spools in case. Funny last weekend my anchor came up heavy??? Had a brand new 20 lb glow downrigger weight hanging off fluke. Some ones knot broke.
HM