Database
[{"_id":"13hu13o13uuo1","profiles":{"1":[1,2,3],"847891":[3,4],}}]
Query
db.collection.update({},[{"$set":{"profiles":{"$arrayToObject":{"$map":{"input":{"$objectToArray":"$profiles"},"as":"element","in":{k:"$$element.k",v:{"$concatArrays":["$$element.v",[11]]}}}}}}}])