Out of pure curiosity, why not move all of it to trash and write it all over again? I must admit that as a theoretical computer scientist it sickens me to death when I hear about "interpretation" of law, especially when given law applies to situations it shouldn't aply when understood literally but it is, for some fucked up reason. I mean - law shouldn't be a poem.
This is going to be a short answer for a long-ass debate.
First: Constitutions do change, my country had the last one made in the 1980. The one before that was 1933, so yes, you can say you can send it all to trash and start fresh, it happens in every country.
Second: Constitutions contain pre-established requisites in order for them to be modified, usually a high % quorum of approval of the congress or parliament. They try to endure through time by these means, they are hard to be changed, hence they stay. THis is all Constitutional Theory and Politics. The "changing completely" of a Constitution is a factual matter, no constitution says "well, you dont like me, then erase everything and draft a new one", they can be changed but are silent about eliminating themselves completely for obvious reasons. Typical means of changing are social revolutions which impose new constitutions, like the one in my country in 1973. Again, this is a factual matter, not a legislative matter. Fichte has a lot written on his on his theory of right.
The American Constitution "cannot be changed, only ammended". The sole idea of changing the Constitution itself, the one signed in Philly in 1787, is an aberration for Americans and thats why they have other bodies of Constitutional laws to support it. This may all sound very weird, well it is, the Common Law system has its positive and negative sides, this is one of the flaws (I sill think its better than the Continental Law system).
