Looking for a suitable resolution, I thought it would be more dramatic if we had two people involved, so I rewrote the verses above:

"This year I will be good," she said,
"Work more and eat a little less,"
Made a vow, a nod of the head.

"This year I'll make sure I'm better fed:
A healthy diet, no excess.
This year I will be good," he said.

"I'll make an effort, won't be late to bed -
It'll do me good to get some proper rest."
She made a vow - a nod of the head.

"I'll save a bit; keep out of the red.
Have to cut down on evenings out, I guess.
This year I wll be good," he said.

Which gives more scope for the final verse:

They met at a party, sharing garlic bread,
Exchanged a number, an email address.
Remembering their vows, they shook their heads.
"Next year we will be good," they said.

And so on to a more sensible lifestyle:

"I'll make an effort, won't be late to bed -
It'll do me good to get some proper rest."
She made a vow - a nod of the head.

Together with a determination to get one's finances in order. Red was an obvious rhyme but I've had to cheat a bit with 'guess' as it's a bit of padding really - but it does suit the conversational tone, I guess.

"I'll save a bit; keep out of the red.
Have to cut down on evenings out, I guess.
This year I wll be good," she said.

Now I just have to bring the two repeated lines together and precede them with two rhyme lines.  (Avid readers will have to wait till Friday as I'm going to the BETT Show to help out on the NATE stand and give a talk along with the Word Chef!)

I'm going to cover the sorts of things we resolve to do better: diet, spending and general looking-after-yourself properly...  So first: food. And we have a perfect rhyme:

"This year I'll make sure I'm better fed:
...
This year I will be good," she said.

And excess seems both a good rhyme and a good fit:

"This year I'll make sure I'm better fed:
A healthy diet, no excess.
This year I will be good," she said.

Having completed the villanelle challenge before Christmas, I've been at a loose end. So, before moving on to something completely different, I thought I would have a go at another one - on the same topic but from a more adult standpoint.

I decided on my first verse and therefore the rhyme scheme quite quickly. With that out of the way, I can see the structure and begin to sketch the development I have in mind.  

 
"This year I will be good," she said,
"Work more and eat a little less,"
Made a vow, a nod of the head.