Okay, first suggestion:
When someone has full enchanted diamond gear they are literally invincible, you could stand still for a minute and someone with a godsword couldent kill you. Fights between 2 fully god geared people never end...
This fact removes any risk involved with getting score and the only way to win the season is for people to mindlessly mine instead of killing those with a higher score.
A solution would be to nerf armor which i think is the better choice if possible or make a way of getting custom enchanted swords.
Since the seasons only last 2-3 months, its very annoying to restart from the beginning every time.
You have to get a wood pickaxe, stone, iron, diamond, you need to find a dungeon where you can settle down, you need to farm sugar canes to get an enchanting table etc and this becomes very tedious when done often.
A way to fix this and make score valuable gameplay wise is to give people a rank the next season, based on the score they had last season. The ranks would basicly get rid of the starting phases of the game and the higher ranks contain the benefits of the ranks below them.
The first rank could make it a little easier to get you started out, im talking a diamond pickaxe, some wood and some food.
Second rank could give you a little armor and some iron.
Third could give you some more iron and some sugarcane so you can get enchanting quickly.
The best reward would be a mobspawner, so you dont have too look for a dungeon to settle down around, maybe have different spawners for different ranks? Maybe solve the "Armor nerf/weapon boost" thing by giving custom enchanted weapons with these kits (would be a great motivation to play)?
The way it is now, either you win or you dont, theres no middleground. When 99% of players will loose, they will have a hard time justifying playing on the server.
Considering most people playing wont be playing for the monthly cash reward, it would be easier for people to justify playing on the server if they get rewarded with a kit next season. The usual reward in minecraft is that you build something awesome, get alot of currency or make yourself a place in the community. This isnt as rewarding when it gets reset every 2-3 months