Traps could be damaged be strong demons or damned souls.

If demons damage trap up to 90% – he will escape and could posses the owner in revenge.

So you should aways keep your trap in good condition.

IF you want to repair your traps by yourself – learn the Repairing traps skill from Tamis.

Each level of Repairing traps allows you to repair trap damaged to 10 multipled by your skill

IE.
If trap is damaged in 20% you need at least skill level 2.
If trap is damaged in 90% you need at least skill level 9.

To repair trap  click on trap detail and than click Repair button in the top-right corner of the screen (in Android version)

Notice: trap mustn’t be deployed otherwise you can repair it.