My experience in this area is limited to reading but it sounds to me like a trace element deficeincy. (just read yates "bible" sounds like nitrogen is needed)

It would probably help to change the soil and possibly buy a bigger pot.

Minimise transplant shock by watering well before and after with seaweed solution then using a slow release fertiliser.

Hope this helps
ree

If the leaves had leaf curl (leaf miner), it is not unusual for them to get yellow and/or drop. In addition, the tree normally sheds some older leaves from time to time. I wouldn't repot it or fertilize it at this time of year but wait until August or when new growth will start to appear.
Leaf miners are active during the warm months (from December onwards).
Rose-Marie

In my experience, citrus trees often get yellow leaves at this time of the year aand while it is a nutrient deficiency, I believe it also has to do with the cold soil and the tree is unable to take up the nutrients. If the leaf miner is your problem - edges curled and a pale green track running over the surface, and they appear to be prevalent this year, I suggest just cut off the affected bits. I have a large Kaffir Lime in a pot and usually once a year it seems to lose its leaves and look sick but I feed it in spring and autumn and its always bounces back with new growth.

I am hartened by this discussion as I have similar problems with mt K/lime. In addition I have a "rust" on the leaves as well but no miners. I have been told that it is to cold for the lime to take up nuitrients but it will come good in Spring. Heres hoping! Thank you to all you who posted on this. 7/7/2011.

My Kaffir Lime has the same problem. We live close to the ocean very mild weather. After planting it (in June)in the sunny location the old leaves are getting yellow and falling. But few newer leaves are coming in the same time. Nursery suggested that I may be watering it too much. Now I am trying to water carefully, but slowly most of the older leaves are gone. Thanks for any suggestion.