Firstly, make sure they’re bled properly.
Yes, new Hope levers will work, but you really need to phone/email HopeTech support to check with them.
You might be able to buy some 2nd hand Mono levers, or even the early Tech levers.
Don’t rule out your existing levers just yet. They might be older than 10 years (Hope stop making spares for items that old), but there’s a good chance that Hope will have stock of the parts you might need, as they’re possibly used on some of their newer parts. It could be that you need new piston seals in your levers.