I was in that dilemma early in the season. The leaves were dropping 1 by 1, about 1 per day. I planted it in MG Organic potting mix with moisture control and thought moisture control was good and would take care of the excess water issue. Plus, I thought it was shipping/transplant shock. If I replanted it then, it will stress the plant again.
The leaves had sign of rust rot, rare in SoCal dry climate but that suggests watering issue. So, I waited, kept it on the dry side but it didn't seem like it will slow down its leaf drops. I repotted it in smaller pot, add more perlite and even let the original root ball dry a little before planting. The leaf drops slow down to 1 every 2-3 days.
I was testing ready made soil mix for other plants and realized the Kellogg one dries much faster than MG. As the plant with only 1 leaf left, I changed its mix to the Kellogg one and it promptly dropped its last leaf. But in 2 days, it was budding again and the whole thing bounced back. I don't know what would happen if I didn't change the mix. May be it can also bounce back without the change.
I also watered very carefully throughout this period except the first time, I pot it up and had to water it thoroughly to get rid of air pocket, even though the original soil was still moist.