Honestly, there is no real way you can keep check on it other than typing them all in. Just open the calculator and continue adding the missing levels.

Well, if you want to keep tabs on it you could make an excell document where you make a first column to type in their current level in, a second column that calculates 100-level to get the needed stuff and then a summary at the bottom that adds them all up. This way you could always keep check on them and just remove those that you have finished.