Hey Shu-Chi! As much as I'm aware of how the game would benefit from switching to Renpy in terms of improved gameplay fluidity, I'm afraid it's not enough of a reason to put a months of worktime to move a project in such advanced state to a whole different platform that I have zero knowledge about. Please believe me that, while VNs might not seem to be a difficult games to pull off, making one version of the game is enough of a headache, especially when you work on it alone making all the writing, coding, testing, editing, drawing, managing two sites and preparing a content for promotion and the supporters.
I must ask though, what is the exact reason you would like to see the game on Renpy? Is there a lack of certain feature or is the game having some technical/ performance issues?