I hate everything about this suggestion. As already discussed, both because of the exponential cost of each level, and because GCL 27 is effectively the max (CPU 300), you have every opportunity to get caught up to the bigger players.
Another limiting factor you may not be aware of is the restriction of only being able to upgrade 15 energy per tick at RCL 8. Before maxing out a room you can upgrade much more quickly than this, but once a player is established with their max number of rooms all at max level, they are limited in how much energy they can continue earning towards their GCL limit.
And even if the idea of a reset was ever entertained, a month is way too short, that would effectively limit the game to 2-3 room play, which would be terrible.