How much should you reinvest in the business?
As a rule of thumb, how much of your profit should you put back in the business?
Live poor, grow faster. Pending on your business the more you can invest in customer acquisition the faster your business will grow. Prior to do that though you need to make sure your systems can handle an increase in volume.
You have not listed what business you are in however after doing a quick check there is a person with the same name as you in Tutoring. If that is the business you are in, based on the information on the website. I would say there are a number of competitors in your industry, investing in technology would be ideal.
And again, if it is the tutoring business you are in. There is a massive market for it, there are marketing companies that specialize only in that area. So customer acquisition isn't an issue, making sure you have the technology to handle it is.