An excellent question. I feel that this is best answered by Irvine Welsh in his piece for the Guardian.
"The vibrant and euphoric yes movement, which, during the debate, evolved from a small base to come within a whisker of a sensational victory, will be massively disappointed that they didn’t manage to get it done.
They will have to cool their ardour a while longer, although anybody believing they’ll stop now is indulging in wishful thinking. Why would they? The process and the subsequent debate, which they won handsomely, took support for independence from around 30% to 45% and heading north. It’s now established as the compelling narrative of the post-devolution generation, while no dominates only in a declining constituency of elderly voters. Yes may have lost this battle, but the war is being won.
Going negative was the only option.
The referendum was a disaster for Cameron personally, who almost lost the union. The Tories, with enough self-awareness to realise how detested they are in Scotland, stood aside to let Labour run the show on the basis they could deliver a convincing no vote. But for Labour, the outcome was at least as bad; when the dust settles they will be seen, probably on both sides of the border, to have used their power and influence against the aspiration towards democracy. Labour voters caught this ugly whiff, the number of them supporting independence doubling in a month from 17% to 35%. In the mid-term, the leadership may have simply acted as recruiting sergeants for the SNP.
As Cameron was at first absent and uninterested, then finally fearful, so Miliband looked just as ineffective and totally lost during this campaign. He became a figure of contempt in Scotland: Labour leaders have generally needed a period in office in order to achieve that distinction.
The referendum galvanised and excited Scots in a way that no UK-wide election has done. Like it or not, unless they come up with a winning devo max settlement, every general election in Scotland will now be dominated by the independence issue.
The yes movement hit such heights because the UK state was seen as failed; antiquated, hierarchical, centralist, discriminatory, out of touch and acting against the people. This election will have done nothing to diminish that impression. Against this shabbiness the Scots struck a blow for democracy, with an unprecedented 97% voter registration for an election the establishment wearily declared nobody wanted. It turns out that it was the only one people wanted. Whether this Scottish assertiveness kickstarts an unlikely UK-wide reform (unwanted in most of the English regions); or wearies southerners and precipitates a reaction to get rid of them; or the Scots, through the ballot box at general elections, decide to go the whole hog of their own accord; the old imperialist-based union is bust.
This country, when it was ever known on the global stage under the union, was associated with tragedy, in terrible events like Lockerbie and Dunblane; it’s now synonymous with real people power. Forget Bannockburn or the Scottish Enlightenment, the Scots have just reinvented and re-established the idea of true democracy. This – one more – glorious failure might also, paradoxically, be their finest hour.”
So how do we get another referendum? We don’t give up. We don’t let them forget about us. We keep the pressure on. We stay united on this cause. We won’t forget that the Labour party betrayed us on this issue and sided with the Tories. Same goes for the Lib Dems, who in my eyes, are royally fucked in England now.