Wendy, I'd guess that watering your in-ground tree three times a week could be the cause of the leaf drop. You don't say what part of S. Calif. you live in, but even if it was still 100F(in the shade)in November, and you had planted it on top of a six foot high sand pile... only then might watering that often be normal.

Myself, I'm still trying to figure out in-ground citrus tree watering...the advice I've seen ranges from water once a week (except when it rains) to "citrus tree roots like to dry out in between watering". The weather and the type of soil make a big difference in water need. So does the fact that a tree with lots of leaves uses a lot more water than a tree with no leaves.

I'd guess that continuing to water three times a week will continue the process of killing the tree. You need to have a way to check the soil for it's moisture content. You can buy inexpensive moisture meters for $10-15. And I've been trying out sticking wooden bamboo skewers into the ground(2-4 inches...the skewers are about 12" long and very cheap at 99cent stores, or supermarkets). Leave one in a few days then pull out and check. You can see how wet the tip is. Check it in a few more days, or a week...and watch how the tip dries as the soil dries. That might keep you from watering too much, if that's what the problem is.

And about leaves growing back, remember that citrus trees have growth flushes 3-4 times a year. You might not see anything happening until the next flush. But as long as there's green under the bark, there's hope.