Contributing to Roth IRA in retirement

I retired a year ago and collect a pension from the State of California. I have a Roth IRA but I am not taking distributions at present. I have started working part-time for my previous employer. While there are rules on how much I can make before it affects my pension, I am not close to that amount.

Can I continue to contribute to my Roth IRA or should I contribute to a regular investment account?

That is helpful! Thanks!