First off, welcome to the forum. Second this an excellent question. I think my first instinct whenever I get into a slump is to look for a new piece of gear whether it be a lens or filter or a piece of software. Anything new that I have to learn to use and use well gets my creative juices flowing. It works, but it is not cheap and sometimes just isn't feasible. Therefore, many times I take on a project. Sometimes it is a project to take a photo a day for a week or month, or a project to take images of a similar style or subject matter. The challenge of fulfilling these projects usually gets me going again and is certainly cheaper than buying new gear.