Yes you can.

Try the following:
!rtimer None 2h 2h Put your text here.

The first 2h is the time till the first output in the guild chat. You can pick any other time you want here, like 30s or anything else.

The second 2h is the intervall between repetitions of the output, which means 2h after the first timer ran out the 2nd will run out, and 2h afterwards, and so on, until the timer is deleted.

The None in front of the times is the timer-class, using None you won't get any output like "Timer xyz ran out!" at all.

After the second 2h simply put the text you want spammed.

I noticed this thread and AlreadyThere's response was exactly what I wanted, a repeat timer announcement. However ... when I used the exact example (above) by AlreadyThere, it didn't quite work in a repeating manner. It announced once, the at each following interval it just kept saying that it was expiring.

Anyone else use it successfully?