I have a project with a DS1307 in it. The time stops (but the sketch keeps running), and I'll have to run the sketch to set the time then put the relevant sketch back on.
Is this because the battery is low or is there likely to be another reason?
Have you tried measuring the battery voltage?
If you using Ds1307 model . It also uses 5v supply & Battery is only for backup.
The problem might be with crystal oscillator
Can you put your code for understanding and How Frequent it stops.
The time stops (but the sketch keeps running),
You have set the oscillator enable bit?