Think of your budget as a working document. The plan is meant to be a guide, it is flexible. If you want to save more, you can either spend less or bring more money in. Sometimes simple lifestyle changes can allow for big savings in your budget, like making your own coffee (decreasing your latte factor), getting a roommate, working out at home instead of a gym, and taking transit instead of owning a car.
You can also use a budgeting or money monitoring app to help track your daily spending and make sure you know immediately if you have room in your budget for that ice cream or awesome pair of shoes.