I gave up on having houseplants a long time ago, because I always killed them ........too busy with everything else to think about them. Anyway, I have a dish garden here that was given to me and it's actually done very good in the 3 months I've had it. I think it may need repotting, but do I do it all in one or each plant individually now?

I would say to leave it alone if it's doing well for you and thriving. Plants should only be re-potted if absolutely necessary. Many people run into trouble when they re-pot a plant that is doing well and really doesn't need it.
You will know when it's time to be re-potted, after it fills up so many roots, it can't hold water anymore, it runs right through without wetting all the roots.
When you do need re-pot, just go up one pot size larger, or, an inch wider than the origional one.
If you ever re-pot each plant individually, use pots that are only 1" wider than each plants root-ball and don't keep them soggy wet.