I'm not sure what it would be called here, but in previous RPGs I have played there is a term called "re-morting".

You would start as at lvl 1, work your way up to lvl 99, and then become a "Hero" (essentially a demi-god). You were welcome to hang out there for all time as a powerful player, or you could "re-mort" back to lvl 1 and start all over again. The incentive (and again, this is based on different game-type) is that you would keep your previous classification (ie: warrior, mage, cleric, etc) and all of the attacks/heals that came with the class. You could then pick a new class and as you leveled up this time, you would be unlocking 2 sets of skills instead of 1. This could be done as many times as you wanted until you had all classes and all skill sets under your belt.

Although it still arrives at a point of finality, it lengthened the amount of time a player would play before reaching boredome. Each time was more inticing because you could use your old tricks to help get the new tricks.

In this game, which is a much more simple game-play, I would suggest that your Base values on everything start at where you left off when you "re-morted" from lvl 15. Doms, Beacons, Mana, HP, would all get stronger each time. Unfortunately, the real draw on the other game was unlocking new abilities...but even Base values rising would give players an incentive to do it all over again.

Some tweaking could be used for sure, but take it for what it's worth - you don't always have to expand upward; sometimes a sideways expansion opens up new possibilities.

Also, leveling (especially at the beginning) occurs way too fast. Progression should be slower, thus delaying the inevitable ennui.

That's true. Lvling in the game I'm referencing took a long time...especially with 100 levels =X