In the Grauniad, Dan Hodges argues that Ed Miliband needs to reach out to"Labour's lost Tories", who voted for Blair in 1997, 2001 and 2005. Which is true in one sense- to win a majority Labour need to get a number of habitual Tories to vote for them not rely on the "progressive majority" which isn't a majority.
Having said that, Blair in 1994 was appealing to Tory voters who hadn't endured Labour misgovernment for 15 years. Miliband can't do what Blair did.
He faces the same problem that William Hague and Iain Duncan Smith faced as leaders of the Conservative Party- trying to reach a centre ground that isn't listening risks alienating the core voters which sinks parties at a low ebb even lower. Hague and IDS both had to retreat to a core vote strategy after early efforts to reposition the party were rejected.
Miliband's best option is to rebuild Labour's infrastructure so that when voters are ready to give them another go they are able to campaign on the ground to win them. Mopping up left wing Lib Dems is part of that as is gaining local councillors.
He probably won't gain anything from this personally but he will his successor a much better chance of being Prime Minister. A fine fraternal gift.