Updates should have three possibilities.
1. Immigration officers process your case and he/she got some information added to the record of your case.Sometimes,this probably implies your case is progressive,or approach to approval.
2. USCIS's systems maintenance.
3. System errors.If you found your case is back to old case information,which is an error.
When you find the update for your case, you may guess its probability,or only way to you is waiting.....