Is it possible for a respondent to return to a form they have previously started completing and update it?

Is it possible for a respondent to return to a form they have previously started completing and update it?

Hi,
I have created a form that is quite long.
 
I don't want to split it into parts.
 
I want a respondent to be able to reaccess a form that they have previously started filling in and add more information.  Is this possible?
 
thanks
 
Patrick