A second Kickstarter would hurt more then help. The only way I can see it working out is if it's introduced as a different module (ie: Add MMO features) which would only detract from the original goal.
I agree. I'd personally have no problem with a second (kickstarter) campaign, but it would have to be very different to the first one. You can't have two kickstarter campaigns for the same thing, as successfully funding the first campaign should mean that all intentions for the project can be fulfilled. If BM were to run a second campaign, then it would have to be for something quite different. As Fawz says, MMO features is one option. Another option would be an expansion, but of course that would be a bit premature at this point.
Certainly, if there is to be another push, it shouldn't be yet. It should be once Sui Generis is much further down the line, otherwise the pitch video would be incredibly similar to the first one. Sure, it would be better technically, but it would still be focusing on the technical side, which is not what would be required for a future pitch video. Once the game is much more developed (in terms of story, characters, gameplay, mechanics) then it may be possible to produce a more gripping "hollywood-style" trailer that focuses on the RPG aspects, which would help to draw in the masses. However, it would be foolish to attempt to produce such a trailer prematurely, given BM's current resources.
One easy option is just to keep the campaign running - i.e. allow people to continue to pledge. Whilst that option is available at the moment, it is rather hidden. Making the usual things a bit more visible - current total, stretch goals (if any), etc. - would improve transparency and may help to boost sales. Certainly, BM should keep thinking about whether there may be any stretch goals that could be added. If they get £x then they can add this, if they get £y then they can add that, etc. etc. - purely from an objective/practical point of view.
The other thing that could be thought about, although may be against BM's philosophy, would be to go down the route of getting people to pay for in-game things (look at Star Citizen, which just raised an extra $4million in 2 weeks by having a sales push spearheaded by a promo offer on one of their ships...). Of course, this may be controversial, especially if not done right. Certainly, it should never be pay-to-win, and you shouldn't be able to pay for anything important that couldn't be achieved in-game with enough effort (which incidentally I believe is also Star Citizen's take on it). Paying for small unimportant (potentially limited edition) things has been done by games like Path of Exile, which allows you to buy incidental aesthetic items, ability to have pets, etc. Not sure whether anything like that could transfer to Sui Generis. As I said before, BM have always been against paying for in-game items, so this sort of thing may be off-limits. Who knows. Perhaps a poll could be done to get an idea about backer opinion...
That said, I suppose we're just speculating - BM haven't exactly complained about the amount of funding they've got, so really we should wait for them to pitch ideas about future funding strategies and then we can give feedback.