No lender is likely to take your name off a loan that you co-signed. The only way to get your name off the loan is to pay the loan off in full.
Your daughter could try to consolidate all her student loans together into one loan through the Department of Education's direct loan program. If the student loans are consolidated, the loan that you co-signed will get paid off in the process. As long as you do not co-sign the consolidation loan, you will not be responsible any more.