Sounds like your asking how to force someone to do something YOU want them to do.
He seems very clear to me that he does not want to return. At least for now. Listen to the words he is NOT saying.
He doesnt want to commit. Do you want someone to be with you out of forced obligation?
You may want to ask yourself WHY you are trying to force solutions?
What was the reason he left to begin with?
Has anything changed to indicate HE has made positive changes to the relationship?
Is it possible you are trying to make the relationship something that is isnt?
Why do you want him to return, if not much has changed on his part?
Just some food for thought...good luck!