Chests refilling isn't a problem. Easy survival is. Here's my 2 cents:
1. Book has sponsors that give you things and the corni gives you things. This is what chests replace, and they do it not horribly. A team of winners in the middle and the active searchers would gain more favor with sponsors, that's why they get more loot from chests. Refilling promotes action to fight for the middle or fight over/race for other further chests.
2. Yes, the middle is a strategy that skilled players in the book use. But the book also states that it is boring, which is why the GM adds dangers! The center should be heavily supplied, but it should also be a point you NEED to defend.
Minecraft does not have an incentive for action, the books do. They need water, food, and protection. If someone shoots an arrow at you in minecraft because you're sitting still in the middle, you can laugh it off, very unlike the books.
How to fix this:
1. No food in the middle, more food in the wild. The middle should not be a safe zone. It should be an arsenal. Gear up, move out, return for more supplies. That's how they did it in the book.
2. The middle is not safe. Since player dangers are null in the middle with a team, there should be booby traps, monsters, and other hazards to INSTIGATE fights. One person under equipped that is struggling to survive CAN'T even go near the middle without instant death. If there was a way for a skilled, quick witted, or smart player could use their skills to get an upper hand the middle would be sufficently riskier to go with the reward.
My idea for #2?
TNT THE MIDDLE!
Have either a tnt minefield that can somehow respawn every night, or just a 1 time deal. Have the trigger either spawn in the middle on the second day, thus making betrayal and sneek attacks better
OR
Make it difficult to get to. where people can't see you.
You DON'T want the make the middle dangerous to be at the beginning. Running straight for the button should not be a good idea unless you're on a team and want to get rid of the tnt, thus you warn your team to get out of blast range.
TL'DR
kill the people in the middle with lava/tnt/mobs/ I don't care, just punish people who can team up with 3+ and have 1 person stay AFK and still live, because that's how it's going now. 2 people can go afk on a team of 3 and still survive till the end.