I am not sure why this is a repeated measures design. Normally that looks at change in a unit given a series of interventions over time. You are doing a simple factorial ANOVA as far as I can tell. If you want to reduce the number of levels the only way you can do that is collapse levels together. Well you can also do I believe what is called a fractional design such as Latin Squares, but I don't work with that so you might check with others on it.