"A while ago" is non-specific. Essentially, if you have a save from before day 100, it most likely will load with errors.
On PC, you can find the legacy save files in this location:
C:\Users\YourWindowsUserName\AppData\Roaming\RenPy\Lewd Town Adventures
When you install the new version, those files should appear in the Load screen. If you see an error, the best option is to start over. There are other ways around that, which take more time and effort. But your first step is to download 0.14.5 and try to load the save.
We have made many improvements to quite a few early-game events (dialogue, animations, music) that could make restarting worth the time. Events like Day 12, the first choice in the mansion, and the MC bedroom in the Prologue are completely overhauled.
That being said, the final version is coming out Aug 1, so waiting until then might be worth it.