According to Tom, Ruy Teixeira recommends that Republicans move to the center on social issues. Based on my analysis with Jeff Cai of 2004 survey data, though, we don't see much gains from either party by moving to the center on social issues (although, yes, the evidence is that the Republicans would benefit, ever-so-slightly, by a move to the left). The real gains would come if the Republicans move to the left on economic issues. Again, this is from 2004 data, and, even beyond timeliness issues, I'd like to see some replication of this result before I fully believe it. Still, I'm surprised that Teixeira seems to be prioritizing social issues and demographic/ideological appeals over more basic taxing-and-spending issues.
The other thing is that positioning isn't all. We estimate that even a large policy shift would only have brought the Republicans an extra 2 percentage points of the vote. Most elections are decided by more than 2 percentage points, so it can sometimes be a good strategy to stand firm and wait for the pendulum to swing back to you.