In the afterword of the latest volume 13 of light novel "Ro-Kyu-Bu!
", author Aoyama Sagu
confirmed that the volume is the last volume for the main story of Ro-Kyu-Bu! He later repeated the same message in his Twitter. He also said that he will write additional spin-off stories for episodes in Ro-Kyu-Bu! that are not covered in the main story. The light novel has been animated in 2 TV series with the second season still being aired.
Source: Aoyama Sagu's Twitter