When a new theme version is released / updated, the translation .po must be updated as well to find the new terms – http://www.marketpressthemes.com/blog/how-to-merge-two-po-files-using-poedit/
Open up your existing language PO file with Poedit software.
Update from POT file
First, change the file type option to
All Files, then select the new wprentals.po PO file from latest theme update folder
Step #4 (OPTIONAL)
Next, you’ll see a mini box which includes all the new strings as well as obsolete string from the new PO file. Proceed by clicking the
Once the import is completed, all the new string from the new PO file will be added and your existing (translated) string will remain intact as well.
Finally, proceed to translate all the new string into your preferred language. Save. Move the updated .po and .mo language file back to wpresidence/languages or to child theme languages folder.