Changing WLAN Password in Squeezebox Touch / Radio

I had my Squeezebox Touch (as well as my SB Radio) connected via WLAN before. Worked fine.
Last months I had them connected via ethernet, Worked fine too.
Now I want to connect them via WLAN again (using in the garden) - and connection fails. (on Touch as well as on Radio)
They recognize the right WLAN-network, try to connect - and fail.
I guess it's for I changed the WLAN password some months ago - but I don't have any chance to type in the new password or to delete the WLAN-network to get asked about the password again.
Any ideas? Don't wanna do a hard factory reset (especially not on the radio for the patches to use lms 8.x ...)

Thanks!