Let's be realistic about this; with a few guaranteed losses coming our way, we will probably have to win over 20 seats from Republicans in order to retake this House this cycle. Even if we retain every seat we hold now (very unlikely), we will have to win 17 seats. A cursory glance over Daily Kos Election's House Ratings shows that to win 17 seats, we would need to win every Tossup, every Lean R and 5 out of 22 Likely R seats.
The Republican gerrymander means we're going to need quite a wave to even have a shot at retaking the House. The field is pretty much set at this point too, so we won't have anymore surprise recruits making races more competitive.
This really begs the question of whether or not going for a majority is worth the expenditure of resources it would require. Considering that almost all of the seats we'd have to go after are at least Republican leaning, we'd have to go after 30-40 seats just to have a decent shot at getting to 17 (or more). This isn't even considering the competitive seats that we'll have to defend. From there, the thinner resources are spread, the less effective they'll be overall. Maybe instead of going full speed ahead for a majority, we should focus on defending the seats we already have, and go on offense for a few that really seem to be winnable.
If we use DKE House ratings as a guide, there are 35 competitive seats this cycle (Lean R, Lean D and Tossups). The Republicans hold 12 of them, while we hold the other 23. There's also a Republican-held seat we're virtually guaranteed to pick up, and two seats we hold that they'll surely win.
So, what should we do with these 35 seats? Put resources into holding the 23 we have if they look like they're in danger, and pick a few of the remaining 12 to really go after. Expand our share of the seats a bit, pour resources into keeping the Senate, and really go after every branch of government in 2016.