Is it worth it to rearm your traps after every single attack?

Traps are pretty essential to maintaining a solid defense for your base.

The more powerful traps cost more to re-arm, but are generally more useful for base defense than the cheaper ones. In particular, the seeking air mine and the giant bomb are both traps that are reasonably expensive but have specific defensive purposes.

There's no requirement that you re-arm all your traps every time they are triggered. If you don't have that much gold to protect, chances are it's going to be a waste of money to set them. On the other hand, as your town hall level goes up, the percentage of your overall raid/collector gold you need to invest in order to reset them goes down significantly. At TH7 and TH8, I never had any problem with the cost of resetting traps.

A better idea is to use some strategy in trap placement - put the traps in spots where they won't be triggered by weak raids (ie, people going for your collectors, or an exposed town hall). Instead, use them to protect high-value targets near the center of your base.

Traps placed further in your base get triggered less often and tend to be more effective. They can't be baited as easily, and raiders have less control over their units later during a raid. Thus, your return on investment for arming them is much better.

if you are struggling for gold then perhaps not all traps are worth it.

At higher levels (TH9+), when you have tonnes of resources and all upgrades cost 5m+, then you hardly notice the cost.

Also if you are getting attacked by mass-hogs regularly then giant bombs are an essential defence