My solution would be:
Load the QVD with a date based where clause (will slow the QVD load if you're not already performing calulations on it) then store the table as your new QVD. To archive the records you excluded with the 'Where' clause reload the old full QVD and this time use a Where clause and a 'does not exist' function before saving this new table as your archived QVD.
There may well be a more elegant solution out there. You could always look at creating a seperate Archiving App to handle the splitting of QVD's instead of taxing your production document.
Hope that helps,
Matt - Visual Analytics Ltd