Here is how you fix it:
#1. No more auto-upvoting. If you want to upvote someone, do it live.
#2 Limit the amount you can upvote to your daily upvote value (weighted by your level) 3x for minnows, 2x for dolphins, 1x for whale. If your daily upvote is worth $3.00, that's the max you can upvote, either all at once or spread out over 300 pennies.
#3 Throttle back self-upvoting to no more than 25% of your daily upvote value.