Most colleges have musical groups - orchestras, bands, folk groups etc. - so if you can find one of those to join then you would have a framework for playing and practising regularly. If the college has a music department then that is the first place that I would enquire.
If the college does not have these there may be other groups in the surrounding area that you could approach.
If you really can't get anywhere with anything like that then you need to organize something so that you play regularly. There are many options such as finding some other players and making a string quartet (which is what I did when I was at university) or just disciplining yourself to play for half an hour four times a week.
Regarding what you would play - it depends on your ability really. Have you taken any exams? If you had, for example, taken grade 6 then the pieces for grade 7 would seem to be appropriate. If not then you will have to decide for yourself. However I will state the obvious thing which is that if you do not play anything then your ability will deteriorate faster than if you do play something.