I led a songwriting class at a camp in Latvia and the one lesson is carry a notebook and pen(pencil). at all times.
One young lady camp volunteer found herself praising God whilst cleaning the toilets at 2am and wrote it down. It's a beautiful song and we did a recording for her.
I personally write very few congregational songs. I seem to be blessed with writing songs about the difficult things.
songs either start with an idea, a need or by playing something new.
Mostly I now write down ideas and lyrics as I hear them in my mind or as soon as I can (if I remember them)
I have songs that I started three years ago that I'm still writing. I have fragment of lyrics waiting to be used.
I have songs such as Turning the Tables which met a need (I searched all the Hymn/Worship books for a song to cover this) that took 30 minutes (10 minutes of prayer included). I have attach the words/chords.
A good cure for dryness can be to sit down and put the pen to paper, whether anything good comes out or not. If you cannot prime the pump, then you might go out an live a bit -- get some rejection, or success, or feel the wind in trees, or learn how the Bible stories play out at the job, or... just live life! Music is about life.
...and when you write words, write real words. If you find treacle coming, or find yourself rhyming "intention" with "comprehension", or find yourself rearranging Redman's words, rip it up. Go ahead, rip it. Rrrrrrrrip IT -- and go out for a walk. Get away from bad text at all cost.