please what ever you do dont force a song, theres nothing worse in my opinion than some one whose obviously tried so much to get a song lyric out that it turns out to be pretty poor.
just wait, i find often a break form writing anything at all helps because when i go back to it i tend to have new perspectives on things, such as just recently i started experimenting more with bluse styles after a break from more poetic/melancholy styles of writing and i personally think ive grown as a songwriter for doing so