I am not sure whether I have understood your question correctly and I am not sure which backend you are using but I assume that you could add
dataset.size = 2000;
to the first line of the function initializeDataExplorer
in the preview_recline.js
file (https://github.com/okfn/ckan/blob/master/ckanext/reclinepreview/theme/public/preview_recline.js#L104).