*Model still must be saved with built in save method before using this snippet.
This will overwrite the originally saved file to v2015, without renaming.
m = Sketchup.active_model
m.save(m.path, Sketchup::Model::VERSION_2015)
Possible parameters instead of Sketchup::Model::VERSION_2015
Sketchup::Model::VERSION_3
Sketchup::Model::VERSION_4
Sketchup::Model::VERSION_5
Sketchup::Model::VERSION_6
Sketchup::Model::VERSION_7
Sketchup::Model::VERSION_8
Sketchup::Model::VERSION_2013
Sketchup::Model::VERSION_2014
Sketchup::Model::VERSION_2015
Sketchup::Model::VERSION_2016
Sketchup::Model::VERSION_2017
Sketchup::Model::VERSION_2018
Sketchup::Model::VERSION_2019
Sketchup::Model::VERSION_2020
Sketchup::Model::VERSION_2021