How to update mod to 1.20.2?

You might be better off making this as a datapack. If you're just adding recipes, you should be able to obtain the same result, and datapacks are both easier to manage and easier to update.

As for mods in general, if MCreator supports a version, you can go to your 'workspace settings' within the workspace, look for the part that says '1.20 generator,' and change it to the new version. However, keep in mind:

• This refactors the entire workspace, so it might take a bit. Also, once you've updated, it's very difficult to backdate, so it's a good idea to make a backup first. (I think the later versions of MCreator do this automatically, but still doesn't hurt to be careful.) 
• Some features may change or need to be regenerated- for example, the latest snapshots of MCreator make projectiles and ranged items seperate elements, and MCreator might not perfectly transfer everything.
• ...And lastly, I'm not totally sure 1.20.2 is supported. They currently support 1.20.1, and I believe the latest snapshots are for 1.20.3, but I'd have to double check. They're a volunteer team, so they've mostly gotta focus on the stable versions.

ik this is a weird fix, but for most mods you can just unzip them and change the supported version number if you dont change from like 1.12.2 to 1.21.11 it should mostly work fine

also this fix is hard to do with complex mods, with recipes and from 1.20.1 to 1.20.2 im 99% sure it will work

https://mcreator.net/forum/123213/i-created-generator-forge-1202