Honestly, if you are working by yourself and without the pressure of a timeline, keep tinkering. Making an eLearning product polished can be a long process, especially if you are making a large course. As long as you aren't completely redoing the whole course you are probably making it better. I think of creating eLearning like writing. The 1st draft is always going to suck a little and it takes revisions to get the really good course to come out.
One strategy I use is to do a full run through and take detailed notes of what I want to change as I play. I then go through and make those enhancements. This lets me keep tinkering and making things better, but because I have a large list to get through I stay a little more focused.
You can also focus some of your creative energy on showing your course to other people and then working on the feedback they provide. They might notice things you've completely missed and provide plenty of things to work on.