I have been out of training for a while, but a couple of years ago that was the case, I'm afraid. I believe you lost the ATPL theory. You may try to convince the LBA to accept your UK JAA credit for a German JAA credit, but they don't have to accept it.
Before you now do all the theory again, check with the UK CAA if they would give you the theory credit if you changed your state of issue back...
Doing the IR theory is quite pointless: it will still not give you frozen ATPL, just a CPL IR, which will make finding a job harder and you'd need to unfreeze your ATPL one day anyway. The ATPL theory includes the IR theory. Can't believe the LBA did not advise you of loosing the credits at the time!!
good luck! IP