If you want to substantially increase your profit, you've got to increase your income, and you do that with marketing. Marketing is not an expense, it's an investment. Paper towels are an expense.
Properly done, marketing returns much more in profits than it costs. If you were at a slot machine that continually paid back $200 for every $100 dollars that you spent would you consider putting in another $100 an expense or an investment? As long as your slot machine called marketing is paying off, you should be putting more money into it, not less. If it's not paying off then you need to fix your marketing or fix what you're selling.
By investing in marketing the potential increase in your profits is limitless.