Who among us hasn't been at that point in the songwriting process where the song sounds good, but wouldn't it sound even better if we added just 1 or 2 more parts? Sometimes this is justified, but many times it just leads to overly busy, cluttered arrangements. One lesson many electronic songwriters (self included) sometimes take awhile to learn is that putting together a good track is every bit as much about what you remove from the song as it is what you add to the song.
It can take time, but it pays to learn to look at your arrangement with an objective eye. Does the part you're adding serve a purpose other than taking up space? Does it really improve the song, or just make it more complex for complexity's sake? How does adding the new part effect the other parts in the song? Does it mask them or make them muddled? Does it ironically make your arrangement sound "smaller" because there is no room for the reverbs and delays to breathe and do their job?
Learn to be brutal about cutting parts out of your song in progress. Don't get sentimental about it - really think about what role a new part would fill and if it is really needed. Take that same approach to the parts already in your song. Experiment with muting different tracks to see the effect their absence would have on the arrangement as a whole. Roll up your sleeves and hack and slash that fat away. If you really hate tossing a cool riff or melody away, cut and paste it into another file and save it for future use in another track. Sure, finding the balance between complexity and simplicity is a bit of an art form, but it's one you can develop with a bit of practice and one that will drastically improve not only the clarity of your mixes, but the effectiveness of your songs in general.