Navigate to Configuration > Database Admin and then select the Data Export tab. The third tab, 'Saved Exports' lets you run existing custom exports that have been saved.

You can run exports direct from the listing of custom exports, or you can edit an existing export (if for example you need to set a date or some other value in the export before running it).

There is no limit to how many saved exports you can have. There is also no limit to what data can be exported in this way, with a suitable SQL query.