Enabling EC2 Instance to handle more users

I have a t1.micro instance running at the moment costing me about $20 a month on average. It is running mySQL, Django, mongo, and apache.

Is it easy to simply upgrade the ram, storage and what not on the instance itself to handle a larger influx of users/visits on the website? Or what is the recommended and cost-effective approach in doing so?

And if I do need to upgrade, will the stack stay functioning and unchanged?