Как насчет того, чтобы сначала преобразовать ваш список в массивы и найти нужные фигуры, а затем изменить их соответствующим образом?
In [2]: lol = [[2,3,4],[5,6,7],[8,9,10],[11,12,13]]
In [3]: lol_arr = np.array(lol)
In [4]: lol3 = [[[2,3,4],[5,6,7]],[[8,9,10],[11,12,13]]]
In [5]: lol3_arr = np.array(lol3)
In [6]: lol_arr.shape
Out[6]: (4, 3)
In [7]: lol3_arr.shape
Out[7]: (2, 2, 3)
# reshape accordingly
In [9]: np.reshape(lol_arr, (2, 2, 3))
Out[9]:
array([[[ 2, 3, 4],
[ 5, 6, 7]],
[[ 8, 9, 10],
[11, 12, 13]]])
In [10]: np.reshape(lol_arr, (2, 2, 3)).tolist()
Out[10]: [[[2, 3, 4], [5, 6, 7]], [[8, 9, 10], [11, 12, 13]]]
# or get the array shape directly
In [11]: np.reshape(lol_arr, lol3_arr.shape).tolist()
Out[11]: [[[2, 3, 4], [5, 6, 7]], [[8, 9, 10], [11, 12, 13]]]