Bedding and appliances when they are no longer usable. For example our kettle (an electric Alessi one) was purchased in 2004 and is still like new. I love the design and whilst it was admittedly expensive (£165 iirc), I think nineteen years is pretty good value for money.
Bedding is replaced when it wears out. Currently we have linen duvet covers etc from Ikea that we bought five years ago when we upgraded to a super king bed, but elsewhere we're using bedding (also ikea) that's probably 10+ years old...although the guest beds aren't used that often!
We did replace a Dualit toaster four years ago after our previous (second hand) one died. The old one was cream but we chose copper this time - partly because it was on sale at the time.
Our saucepans etc are copper - a mix of vintage and new - collected over the past ten years. Before that we'd had stainless steel from Debenhams for fifteen years. We have two sets of cutlery (both Culinary Concepts bought at the 2004 Ideal Home exhibition) which we've no plans to change as they are still in really greet condition. Dinnerware, again we've got two sets both around twenty years old - one is a rustic style from Portugal and the other from Debenhams bought on clearance for very little but I love both.
We have lots of towels (many from Liberty) I got new on ebay ages ago and haven't started using them yet as our older ones just won't die!
Furniture is antique/vintage, as are our mirrors and many of our decorative bits and bobs. Because we buy stuff we love, we tend not to swap things out - some stuff we've had almost thirty years (we're in our 50s and married at 21) - but occasionally we add something new to mix things up a little and we did offload a lot when we downsized in 2018.
My weakness is textiles so I'm always either buying new cushions or else the fabric to make more. We finished some building work (DIY) last year and I treated myself to loads of cushions/fabric to complement the newly decorated spaces. The old ones get sold online so I don't feel as guilty for replacing them 😉