I currently am using Twine 1.4.2, because I misread when I downloaded it. At first I didn't think much of using it, so I started a story on it, but now I'm thinking about upgrading to the latest version, and I was wondering if I'd be able to do that without losing any of the progress I've already made on my story?
The Twine 2 application does not currently support the importing of either a Twine 1 Story Project file or a Story HTML file created using Twine 1's build option, but there is a manual process that you can use to convert your exist story project into something that the Twine 2 application will recognise.
The following lists the issues that need to be overcome and the steps to do so.
1. Sugarcane is not supported on Twine 2.
You can get around this issue by switching your existing Twine 1 project over to using SugarCube v1.0.3, which is similar to Sugarcane although there are differences that will need to be resolved later.
1a. Download SugarCube 1 from this site, you will want the Twine 1 related release which is the first of the two links within the Downloads section.
1b. The Adding Formats section of the Twine 1 Guide explains how to install the contents of the ZIP file you downloaded in point 1a.
1c. Make a copy of your Story Project TWS file then open that copy with Twine 1 and use the Story > Story Format menu items to change it to use SugarCube.
1d. Use the Build > Build Story menu items to create a new Story HTML file, give this HTML file a different file name than you would normal use so you can distinguish it from any other story HTML file you have previously created.
2. Converting Twine 1 Story HTML file to Twine 2 Archive file.
In the Utilities section of the web-site you downloaded SugarCube from there is a link for downloading a tool to do this conversion.
2a. Download the ZIP file and extract its contents onto your hard-disk.
2b. Open the contained HTML file in your web-browser and follow the instructions.
3. Importing generated Archive file.
Run the Twine 2 application and use it's Import From File option to add the Story Project contained within the Archive file (you just created) to your list of Stories.
4. Fixing the differences between Sugarcane and SugarCube
Without knowing exactly what code you have written in your story I can't tell you exactly what may need to be fixed, I can only suggest you test your new story project and use these forums to resolve any issues you find.
5. Upgrading to SugarCube 2.
This is an optional but recommended step because as explained on the SugarCube 1 web-site the 1.x series has reached the end of it's development cycle and is now only getting bug/security fixes if they are needed.