Knives don't stay sharp, you need to keep them sharp. There's lots of info on Youtube on this, and even if you spend a lot on knives you still need sharpening skills. I'd see what you can do with your current knives before spending on new ones. I use a couple of cheapies the wife got with some vouchers at Tesco a few years ago. They take a good edge, which I keep with regular use of a steel and an oilstone.