I don't know one in San Diego. You might call Mission Imprintables as they would probably know.
Here's a large sized shop that does it in Orange County. I don't use them but I've been in the factory and they do it all. They charge .15 for one label, .20 for two, all under the tape, including removing the existing label.
Products
Also, if your orders are large enough, SKIVA Graphics, a large screen printer in Carlsbad, can relabel and screen print.
Relabeling Service in San Diego, CA?? 
