Depends on the quality of your chain. I won't quote Oz standards - but I guess you have two types of chain in the US - locally made tested good quality chain (usually branded with the makers name and/or spec) and there is cheap
Chinese chain that might be OK for a runabout or the like.
If it is the former - consider having it regalvanised. Your good quality chain is an investment and if it is not worn (visually inspect EVERY link) or overstretched, the galvanising works will acid wash it and galvanise it. Maybe you can do your anchor too if it needs it. My regalvanising cost less than AUD$3.00 a meter. Cheap
compared to the cost of new (Ozzie) PWB short link tested chain.
If it is the latter and is rusty - replace it. Perhaps replace it anyway.