That's not how it works. If the crowdfunding campaign fails, nothing happens.
No money gets exchanged, the project doesn't move forward, and Luke will have
to launch an entirely new campaign (assuming he can; otherwise he'll have to
spend some time coming up with a new game plan, possibly years).
Also, it's not possible to change the campaign's funding goal in the middle
of it. If you could suddenly reduce your funding goal to make the campaign
succeed, and did so, that would be fraud. So assuming people can cancel their
orders (I don't think you can), telling people to do so would only make it
almost impossible for the campaign to succeed because you're just cutting off
roughly $35,000 of pledges.
What should be done, and what is being done, is focusing on raising the
$150,000 goal. That goal can be achieved; please remember that many people
might be waiting until the last minute to contribute for one reason or
another. If the campaign fails to meet its goal, no money will be raised
(i.e. not a problem for backers), and Luke can decide what to do to salvage
the situation (possibly with a smaller crowdfunding campaign for example) at
that time. There's no need to plain for failure now.
