Blood & Smoke is the latest edition of Vampire: the Requiem and it works out experience points a little differently than most. Rather than earning a full experience point for an action, you instead gather partial XP called beats that combine into a single experience point on a 1 for 5 basis allowing you to slow down its accrual and reward multiple aspirations and conditions rather without flooding your players with experience points.
Naturally in a LARP of 20 players it starts to look a little complicated so here is an example of my LARP's excel spread sheet which I update several times a month to reflect my player's actions. After every session I tally up the experience points and award them (typing them up in people's Downtime threads) and then I tally up the remaining beats and add them to the next month's Roll Over column.
Since people are also capped at earned experience points equal to Campaign Months x 2 (i.e. you can only earn a total of 12 XP by the end of the sixth month), I also need to pay attention to such caps though no one has ever met that growing cap yet.
Here's an image of the spread sheet columns to give you an idea of its complexity though naturally it's far longer as there's 20 different players at present (click it to enlarge):