Hmmm…I don’t know!  I lose interest all the time…and then I find something, dream something, see something that makes me kick myself and get back in there.  I think it’s pretty human to lose interest in all things familiar.  It just sometimes happens.  I’ve found forcing myself to use mediums I thought I could never pull off has been really helpful and surprising.  A lot of times if I do not like a new project, it forces me to go back to something I know I can do pretty well and that can be fun.  I hope that helps at least a little!