You may be tempted to solder your own new leads to replace the black and red wires that are pre-soldered to the piezos. The piezo acts like a big heat-sink, and it is nearly impossible to get the area hot enough to get your solder to stick.
I managed to get it done, using a great deal of flux, and getting a descent blob of solder stuck to the end of my leads, and then lowering it down to the flux-ed areas. Took some time, and not very pleasant. You'd be better served slipping some heatshrink tubing down your piezo line, and use the existing leads. Then slide the heatshrink, up and over the joint. Much cleaner, less panic.