So NI comes under UK law, I found this, appears to be UK legal advice (but I am not a lawyer, even in nightmares, so I am passing this on without endorsement):
in a compulsory redundancy situation, the issue is whether at the time of the redundancy there was no longer a need for the role to be done. Things can change and, post redundancy there may then be a need for the role to be done hence advertising would be fair. An employer would have to demonstrate at tribunal that at the time of the actual redundancy that role was not required.
I would guess the closedown for refurb is also a key part, the new company may be claiming to just be buying the assets (property, fittings etc) and the old company is closing when the premises does (although they could argue that the role was not required during the refit time, if that was weeks/months it may add fuel to their fire).
This would allow them to hire new staff for their new company, but that's just my take on it. I think your length of service with the old company is critical as well, under 2 years and your rights are far more limited.