From Attributes > Embedded Data Mappings select rerun metadata extraction for existing assets. You may select one or more mapping to rerun. Be aware that any attribute involved in a mapping will be overwritten with the value in the embedded metadata so only select those you require.
You may select a single Asset ID to rerun or alternatively you may select a range (the Lower ID is the first in the range and the Upper ID is the last in the range).
Click Run Extraction to begin. This may take some time if there are many assets to process. The page will refresh to update on the progress of extraction.