Besides, you're going to run out at some point.
On my current analysis of the concept of genre, it is a 16 dimensional space with a volume of [6 x 6 x (4x4x4x4x4x4x5x4x4x3) x 8 x 7 x 4 x 4].
Which gives Pigfender approximately 31,708,938,240 unique genres to look forward to.
And you know when you and I hit our 30,000,000,000th pencil cup we're going to celebrate and we won't be thinking about the cuppa that got away.
I see no harm at all in revisiting genres, provided the plots don't overlap.
Wait. Unless it was a sequel or part of a trilogy!