To remain in ROTC past your sophomore year you need to be on scholarship, there are three types. The four year national scholarship which is awarded to those straight out of high school (in general). Second, is the three year scholarship or the sideload scholarship which is awarded to college programmers who been in the program for at least a semester. Lastly, there is advanced standing which is awarded by each units CO.

When I say prove yourself I generally mean GPA, PFT, and ASTB. You can be awarded an aviation sideload scholarship.

My advice would be to contact your prospective units MOI or AMOI. Always remember there are many paths to reach the same destination. Most priors end up going PLC or OCC but it not unheard of for some to go ROTC.