Grado just like any good manufacturer do not retip, they get your old and give you new cartridge with special discount (only if you send your old cart to them).
Grado XTZ is Signature Model, top of the line cartridge from Joseph Grado himself, it's his best, but discontinued model (styli still available). Can be different from you model, but it's a killer cartridge (I've mentioned that only because it's the best Grado with replaceable stylus that I know and own, the stylus alone is about $500).