I will admit to ignoring the question first-off because it looked like a plea to shortcut your homework.
I'm not surprised you couldn't find any resources as case law because I don't believe that it is the true intention of the Act. If the purpose of the group exercise is to test your ability to construct and present a persuasive argument 'against the odds' then I can understand it.
As you've found the relevant part of this Act is clause 4:
Where the court is satisfied on an application under this section that it is reasonably necessary to carry out any basic preservation works to the dominant land, those works shall be taken for the purposes of this Act to be reasonably necessary for the preservation of the land; and in this subsection �basic preservation works� means any of the following, that is to say�
(a) the maintenance, repair or renewal of any part of a building or other structure comprised in, or situate on, the dominant land;
(b) (c) (d) [deleted as not relevant to your situation]
but this subsection is without prejudice to the generality of the works which may, apart from it, be regarded by the court as reasonably necessary for the preservation of any land.
I agree with your proposed approach as being one way of arguing it (maintenance = renewal of any part of a building). The only bind is there would need to be something there already. A pile of stones, perhaps? - you are maintaining a pile of stones by renewing them.
The only alternative I can suggest is picking up on the words 'preservation of the land'. If you could argue that constructing a new building helps with preserving of the land underneath (from erosion by rain?, from contamination in the event of nuclear fallout?, [you could create several scenarios], then the wording of the Act seems to fit your case.
I guess it depends whether this a 'management exercise in persuation skills'