dutasteride has a long half life so you may just need more time.
In the meantime the following are are all good at increasing libido:
yohimbine hcl 8-15mg/day
deprenyl 5mg/day
arginine 3-6 grams/day
proviron 25-50mgs/day (note proviron is an androgen and may accelerate hairloss)
For purely getting it up, I have had success with cialis.