I bought some light up sketchers years ago (they came from the kids section and they fit my feet) and the battery life has gone down hill due to not being designed for wearing long term by an adult…
I would like to replace the battery, charging circuit, and add a microcontroller so I can monitor the battery life and change the colors of the leds in the shoes via an app if possible.
That’s doable…you’ve got a bunch of options. Have you tried getting access to any of the components in your shoes yet? What battery is in them now, and what form factor are the LEDs?
Here’s an example of one way to do it, although you could use any of a number of microcontrollers. WS2812s (Neopixels) are kind of the easy way to get where you’re going. There are also ready-made, inexpensive charging boards you can use with a LiPo battery, as well.