if you get denied, first you need to make sure the reason why. if it was an admin error on part of the USCIS, then one can apply and will not have to pay the $465 again
however, if one is denied and it reason was the fault of the applicant (lack of evidence or such) then one can reapply but would still need to pay the $465 again.
what is best, is to make sure that you have all the main requirements of DACA met. remember that you can not use affidavits for the main requirements. one can use affidavits to cover small gaps of time within the 5 year period between 2007 to 2012.
even if it takes a while, it is always better to send as a complete evidence package as possible to avoid receiving a RFE. there have been new reports that people have used video gaming logs such as from XBOX as evidence. so take the time to look into every avenue possible in gathering evidence.