Personally, I'd do nothing. I'd rather have the money in a Roth. Once you retire, you can take it out tax free, and there are no RMDs. You will already have a lot of money in a traditional IRA (made up of your 401k rolled over to an IRA) or still in your 401k, so I'd think the "tax diversification" of also having money in a Roth would be good. The deal is you either pay tax on it now, or tax when you take it out. Yes, we hope to be in a lower tax bracket in retirement, but really, you're talking a few hundred bucks here, AND if you do end up needing to take RMDs, that could bump up your tax in retirement.
You could recharacterize a portion of your Roth contribution as a traditional IRA but I would wait until next year [Edit: up to April 15th] to do that so you know exactly what your MAGI is, and exactly how much you are eligible to contribute. It is pretty easy to do, but call up your IRA custodian so they can walk you through it on the phone. I don't know that I'd convert back to a Roth though - I'd do that if you were recharacterizing because you earned too much to qualify for a Roth, not because you earned a low enough income to qualify for a Traditional (deductible) IRA.