On the same day of the week (I chose Mondays), week by week, go on Coinbase and get the updated ranking and stacking of the top 5 coins based on weekly returns.
For any coin that appears on the top 5 list the second week, do nothing. Let the investment ride another week.
For any coin that does not appear on the top 5 list the second week, sell it and use the proceeds to buy one of the new coins on the list.