First of all 15 lbs is no "only". That's a good amount a weight to have lost! So congrats!!! Every pound down is one less to lose afterall!
Secondly, 105 lbs in a year is an ambitious, but not impossible goal. However, I must warn that many people have stated that their weight loss has stalled at certain points, and that losing the last few pounds often takes a little longer. So, even if you "only" lose 70 lbs this year, wouldn't that be fantastic, too?
Best of success!!!