The last time I checked (which was a few months ago) Optomcas will require everything to be re-submitted if you wish to apply again next cycle. Maybe this could change (although I highly doubt it) but you can always call them up and ask.
On optomcas it states:In order to have optomcas sumbit your application everything must be filled out which includes LOR. They clear you application each year so unless some changes are made you will have to resubmit your LOR.
I suppose that is true. I'm just worried cause I'm graduating this year and its going to be hard to get proffesors references again.I think that only refers to you waiting for your letter-writers to fill everything out. Cuz you know how you have to designate the people first and then when the ppl finish filling it out the status changes to completed. I think you will need to designate them again if you're going to reapply. However, it's a good question whether or not the schools you're reapplying for keep your letters. But what if you apply for a school that you didn't the previous year? You'll need letters for them. So it might be a good idea to submit them again.