Aerender does what it says on the tin: it just renders. It can save a comp after rendering if there's a post-render action like setting proxies, but AFAIK it has no other capability to modify projects (figures, because it is available to put on as many machines as you want, so they don't want to be giving away a program capable of editing .aep files).
To modify an After Effects project you have to have a licensed instance of After Effects running. You can do it with extendscript in headless mode, so AE will run, but won't show the UI, but you can't run extendscripts without AE installed.
A better way to do what you want is to use the new data-driven animation features. You can use an expression so that the content of the text layer is linked to an external data file. Changing this file (which can be JSON, a piece of JS or just plain text) will change the contents of the text layer.
Using that workflow you
- Set up your template with AE,
- set the data file with Node (or whatevs) render,
- replace the data in the file,
- move the previous render,
- render again, change the data, render, and so on.
One gotcha with that technique is that you have to move the rendered file between renders, because you can't change the destination of the comp in the render queue so it will try to over-write the old one.
If you're using older versions of AE you can still use external data files to drive the contents of a text layer using
eval() in an expression. The technique is explained here (full disclosure: my personal blog).