No easy solution to downgrade the project, which is also not supported anyway by Mendix.
1) Fake the version number; if you have changes in the model which are not backward compatible between two versions, the older model won't understand your newer model
2) redo your stuff in 7.13.1 (adviced solution if redoing is not that much work, otherwise consider 3)
3) update your 7.13 through the SDK by reading your model of 7.17.2 also by the SDK (domain models, documents (mf's, pages etc). see https://docs.mendix.com/apidocs-mxsdk/mxsdk/generating-code-from-the-model.