I'm under the impression that DMDO reduces back to acetone after it oxidizes something, so could you use the acetone as a form of catalyst?
Oxone oxidizes acetone to dimethyldioxirane. The latter is reduced back to acetone when it has epoxidized an alkene. You are not obliged to choose for acetone, other ketones can work as well. For instance: Wang et al., An efficient catalytic asymmetric epoxidation method. JACS 119 (1997) 11224-11235. They developed a ketone, based on fructose, which catalyzes the epoxidation of the alkene by oxone.
This group has written several articles using the same catalyst over and over again (you can say they milked it out pretty well), studying the effect of solvents, pH etc. In their case, MeCN seemed to be a good solution. Also keep in mind the pH of your reaction mixture. The oxirane ring of our phenylpropane epoxides is very often pH sensitive. Several articles covering that subject as well.