If you are certain you have the save files (perhaps you found the save folder), you can manually move saves between installs. The general principle is:
C:\Users\[Your Username]\AppData\LocalLow\DeveloperName\InsectPrisonRemake\ insect prison remake save data
Steam usually utilizes the standard app data directory or the Steam user data folder for cloud synchronization. If you are certain you have the save
The location of save data can vary depending on the platform on which you're playing the Insect Prison Remake. Here's a general guide: insect prison remake save data