The electorate is polarized with only about 12-15% of people uncommitted to one party or the other. Elections are determined by these uncommitted people. These uncommitted people tend to vote based upon what their friends tell them. Many people do not vote policy they vote likability. Because it is easier to understand than policy is. Obama is still personally likable even if he is an unsuccessful president. If the economy improves he will likely be reelected, and if it declines again, then not. Key factors will be the price of oil and the conflict between Iran and Israel, and how well his opponent connects with voters after the convention.
If I had to bet money I would say that at present he will win by a very thin margin, if the issue with Iran does not peak, and if there are no surprises.