itch.io

You can always try, but often there are enough changes that it's a bad idea.  I think there was one around .55-6 that requires a new save for the new content, if nothing else.

There's a slider for growth speed in the settings.  Might be what you want.

It's also worth pointing out that when you right-click to multiuse items, it lets you select a target as well.  Helpful when you start drowning in potions later.