EDIT: You need to separe sprite's initialization and display
- Make your sprite ONE time in your create method for example
- Update your sprite's height on tap
- Draw your sprite in your render method
Your code won't do what you want because you make a new sprite at every tap. You want to have a single sprite which you resize in height at every tap.
You should have something like this
// On tap
stickSprite.setSize(stickSprite.getWidth(), stickSprite.getHeight() + addValue);
This way you could draw your sprite easier like that
// On draw
stickSprite.draw(batch);
The setSize will resize your texture to the size you tell him. It will do it perfectly for your unicolor texture.
Hope it helps