Yes you can. In fact, it's common when people first learn about Reimbursify that they already have visited an out-of-network provider multiple times. 

Most health insurance companies allow a reimbursement claim to be filed up to one year after the date of your service. The app notifies you when selecting a date of service exceeding that 12 month period. 
We are, however, starting to see some insurance plans limiting the filing window to six months, and in some cases three months. This is a function of your specific plan and Reimbursify has no control over this filing window or what your insurance company ultimately accepts or pays out to you.

We recommend reaching out to your employer (if you have an employee-sponsored plan) or directly to the insurance company for exact details.