Happens to me all the time. Things I do during my 'slumps':
- read old copies of magazines. You forget about some of the cool articles.
- bench clean-up and reorganize
- practice painting (grab an old kit from the junk box and start practicing air-brush stuff.)
- spend more time on the forums
- test new techniques/tools/products - grab junk kit parts and test out new ways to mask, scribe, fill, polish ,weather, etc, etc.
- buy/build a new tool - a spray booth? a small hobby lathe??
Just a few ideas/things that work for me. They all keep me close to the hobby, but away from the frustrations of building the kit. Eventually the motivation returns and I charge head-first into building another "masterpiece" that falls short of my hopes and intentions! They may not be perfect (in my eyes), but they are getting better...
Murray