I figured out how you recompile your edited levels. I was a dumb dumb and hit the wrong button.
But still, why ReggieNext doesn't already have this implemented into the program is strange.
Here's the steps for anyone else having trouble:
1. Download Uwizard:
http://wiiubrew.net/sdm_downloads/uwizard/ (The download button is at the bottom)
2. Open up Uwizard and click on the "Archive Manager" tab
3. Click "Compress SZS", select your Level and name the output file.
4. Grab some lunch, take a walk, go to a game, see a movie or even go to freaking bed because this compile is gonna take a LONG time. (Usually about 1-2 Hours)
5. Then follow this tutorial:
https://gbatemp.net/threads/tutorial-custom-levels-in-new-super-mario-bros-u-fw-5-3-2.395758/
6. Have fun! : ) else i steal yo monies