Hi Ian,
Unfortunately, soapUI projects are not saved anywhere automatically unless you tell soapUI to do that.
You can either hit Ctrl+Alt+S (to save all projects) every now or then or choose to have soapUI automatically save backups for you. Go to File->Preferences->UI Settings dialog and check Create Backup option. You also need to define a folder where to keep backups and set AutoSave Interval to a non-zero value. I guess you may want to use this autosave option.
Cheers!
/Nenad Nikolic a.k.a. Shonzilla