Picture was taken with my 70-300mm which is much sharper.

I need some advice when it comes to lenses. Right now, I have an 18-135mm f/3.5-5.6 that came with my old Nikon D80. This lens is more than 10 years old and as a result, the pictures that I take with it are usually less sharp than the ones I take with my 70-300mm. I have been looking at replacing it with the Nikon 18-55mm f/3.5-5.6 VR II since I already have the 70-300mm range covered. Would there be a huge difference in upgrading to this lens and would it be better in low light due to having VR II? Also, I’m currently using a Nikon D7200.

This was taken with the 18-135 and while it isn’t bad, it just isn’t as sharp.