As an aside: a liquidated damages clause generally has to spell out either the amount or a mechanism for calculating it. An open-ended liquidated damages clause in your lease is probably unenforceable, since it would allow the landlord to penalize you arbitrarily if you broke the associated condition. Quoting Wikipedia:

In order for a liquidated damages clause to be upheld, two conditions must be met.

First, the amount of the damages identified must roughly approximate the damages likely to fall upon the party seeking the benefit of the term.

Second, the damages must be sufficiently uncertain at the time the contract is made that such a clause will likely save both parties the future difficulty of estimating damages.

Of course, there's no reason to specifically antagonize your landlord or to demand that he remove the clause from your lease, but I wouldn't fret the unspecified liquidated damages too hard. If you cause actual damages or materially interfere with the sale of the property, worry about that, instead.