There should be nothing different between submissions from 2013 and 2014 - what do you mean you are unable to access them? Where are you going and what are you seeing and not seeing?
A "filter" applied could explain not seeing a data set - see this FAQ about "missing" data from the View Responses tab and see if it helps: http://forums.adobe.com/docs/DOC-4071
You probably have more than 5,000 responses. You will need to duplicate your current form, including responses, then add 2013 to the name. Then go to your active form and delete responses recieved prior to 2014. This way you have an archive and a clean slate. thanks!
That is a good thought - COM Outreach, let us know if that was the issue, it is always good to know if things are not made clear enough.