If you have died in-game, but you want to play again using the same Minecraft account, you can use a revive. You do not need to be dead in-game in order to purchase revives; you just won't be able to use them unless you are. Once you purchase a revive, it will be added to your in-game account, available for you to use at any time.

To use a revive, simply type the command /revive use in-game. You can also transfer revives to other players by using /revive transfer <name> [amount].

Using a revive is pretty much equivalent to logging into the server with a new Minecraft account - you will be teleported to the spawn point of the server, your game mode will be changed from spectator back to survival, and your player-specific progress will be reset*. This has the benefit of not requiring you to buy a new Minecraft account in order to be able to play again, which is what you would have to do on a 100% vanilla hardcore server (as well as change your IP address in the case of death-IP-ban servers).

*Here are the specifics regarding your player-specific progress being reset:

• If you have a respawn point set, it will be deleted from your player data, meaning the exit portal in the End will teleport you to the spawn point of the server instead of said respawn point, and you will not be able to teleport with the /home command until you set a new one.
  
  
• Your last death location will be deleted from your player data, meaning recovery compasses will not point to it.
  
  
• Your ender chest contents will be cleared.
  
  
• All advancement progress will be revoked.
  
  
• If you toggled off phantom spawning for yourself, it will be toggled back on.
  
  
• All unlocked recipes will be undiscovered.
  
  
• All statistics will be reset, except:
  • Games Quit
  • Number of Deaths
  • Time Played
  • Time Since Last Death
  • Time with World Open
  • Killed by Mob
    
    
• Any tamed animals you own will no longer be tamed.
  
  
• Any trial chamber vaults you unlocked will be able to be unlocked by you again.
  
  
• Any land claim blocks purchased from the Estate Agent NPC will be removed, meaning you will have the starting 200, just like a new player.
  
  
• Any items and claimable coins of yours in the auction house will be deleted.
  
  
• Any auction house sell slots purchased from the Auction House Clerk NPC will be removed, meaning you will have the starting 10, just like a new player.
  
  
• The "Server Rules", "Help Manual" and "Frequently Asked Questions" books and 16 bread given to new players will be given to you again.
  
  
• If you used your one-time-use random teleport (/randomtp), you will be granted another usage of it.
  
  
• Your PvP protection timer will be reset back to 1 hour.

Note: If you are banned from the Minecraft server, you will be unable to use or transfer any revives, as these actions require you to type commands in-game.