The easiest way is to clone it before editing it, but after the plugin is initialized:
var $defaultTable = $('#spreadsheet').clone(true);
Then, when you need to reset, use:
$('#spreadsheet').replaceWith($defaultTable);
EDIT To process multiple resets, you need to clone it when replacing it, so as not to work with a modified version of futur, for example:
$('#spreadsheet').replaceWith($defaultTable.clone(true));
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