Sorry, Mideia, I must have missed your PN... But you're right, "Schatz" means "treasure" or as well "darling". Depends on the context
Btw, the original text contains some mistakes...
It should be:
Bis zum nächsten Mal
Ich habe dich sehr sehr gern und lieb tschüss
Ich habe dich sehr gerne mein Schatz, mein Liebling.
Even though the translation is already accepted, I would still change it. Oh and Lily, I just saw a minor mistake in the English translation: it should be "my darling" or "my treasure" instead of "my life". Just if you want it to be perfect..