Can you replace a shower handle without replacing the valve?
It depends on what valve you have. What you're looking for is called a shower trim kit. When homes are built and the plumbing is done the shower valve is installed. Later the customer/homeowner picks out a trim kit which is the plate, handle and shower head. Depending on what valve you have there may be a good selection of trim kits or none at all. There is a bit of savings with the trim kit because you're not paying for a valve.