They're already in there. For the next beta at least.
From the user manual (these are the "Common" export items, available to all exports including receipts):
timestamp: The current time and date. This item will always contain both the time and the date.
preftimestamp: The current time and date. This item may only contain the time, if the Show dates preference is disabled.
time: The current time.
date: The current date.
eventtimestamp: The time and date the tournament started.
eventpreftimestamp: The time and date the tournament started. This item may only contain the time, if the Show dates preference is disabled.
eventtime: The time the tournament started.
eventdate: The date the tournament started.
eventname: The tournament name.
description: The tournament description.
notes: The notes for the tournament.
league: The tournament’s league.
season: The tournament’s season.
buyininfo: A description of the buy-in amount. For example, “$50 Buy-in”.
rebuyinfo: A description of the rebuy amount. For example, “$100 to Rebuy, through round 3”, or “No Rebuys”.
addoninfo: A description of the add-on amount. For example, “$50 to Add-on, through round 3”, or “No Add-ons”.
rebuys: The number of rebuys purchased during the tournament.
addons: The number of add-ons purchased during the tournament.
startingchipstack: The number of chips each player receives in the default buy-in profile.
players: The number of players who participated in the tournament.
pot: The total value of the prize pool.
payouts: The number of prizes awarded to specific ranks.
starttime: The time the tournament started in the format specified on the Preferences Tab.
endtime: The time the tournament ended in the format specified on the Preferences Tab.
elapsedtime: The amount of time that has elapsed since the tournament started.
playingtime: The amount of actual play time that has elapsed since the tournament started. Note that this sums the time for each round up to the current point in the tournament. If you change the schedule, set or reset the clock, or skip levels during a tournament, this value will not necessarily be accurate.
history: The tournament history (see Tournament History).
actionsummary: A concise summary of the actions that have occurred in the tournament (see Action Summary).
gamename: The Game Name of the first round of the tournament.
gametype: The Game Type of the first round of the tournament.
charset: The content type that the export token values are determined to be.
Additional items for receipts:
receiptnumber: The receipt number.
salesperson: The sales person.
name: The name of the player, formatted as specified by the Name Format preference.
nickname: The Nickname field of the player.
firstname: The First name field of the player.
lastname: The Last name field of the player.
streetaddress: The Street address field of the player.
city: The City field of the player.
state: The State field of the player.
zipcode: The Zipcode field of the player.
country: The Country field of the player.
phone1: The Phone1 field of the player.
phone2: The Phone2 field of the player.
email1: The Email1 field of the player.
email2: The Email2 field of the player.
notes: The Notes field of the player.
id: The ID field of the player.
profilename: The name of profile (Buy-in, Add-on, or Rebuy) that was used when the transaction was made.
tablename: For buy-in receipts, if the player is already seated (in the case that your settings allow the seating of players who have not yet bought-in to the tournament, or you utilize the Auto Seat option), this will represent the name of the table at which the player is seated.
seatnumber: The seat number at which the player is seated. See previous token tablename.
seat: The table name and seat number at which the player is seated. Essentially, this is a combination of tablename and seatnumber.
itemN: The label for an item on the receipt. Each item listed on the receipt will have a corresponding itemN token. For example, a buy-in receipt with no other fees will include an item0. A buy-in receipt that also contains a bounty chip fee will include an item0 and an item1.
amountN: The amount for an item on the receipt. For each itemN on the receipt there will be a corresponding amountN.
rakeN: The label for one or more rake values on the receipt.
rakeamountN: The amount for a rake on the receipt. For each rakeN on the receipt there will be a corresponding rakeamountN.
total: The total, or sum, of the receipt.