The toughest part may be to get the letters of recommendation (LOR) if the professors have only a vague memory of you. I took some time between undergrad and grad school. I took university graduate courses as a "special " student part time. I had to pay the tuition for these courses, ouch, because I was not supported, but I did get to know and impress the professors, and I later asked them for LOR's for grad school. It also had to take the GRE's again. It was a long arduous process, but it can be done.