Once DCFS makes its determination, the only way to reopen that specific decision is through an appeal challenging the finding.
That said, anyone can make a new report to the hotline at any time. A new allegation starts a brand-new investigation with its own 60-day clock, even if the earlier report was unfounded.
If reports keep coming in, keep your own record of each contact, each investigator, and each outcome. That history often matters in a later hearing or custody dispute.