I have this fig tree in a pot for about 12years or so, it was my fathers. It still produces about 30-50 figs every summer but has minimal growth. My question is would  it be okay to re-pot now(spring) or to hold of till fall!

You may shock it now.

In the fall when it goes dormant take it out and cut off the lower 1/3 of the root ball. Throw that in a pot with good soil. Could get another tree from that. Trim some off the sides. Throw that in a pot with soil and another tree could emerge. Repot with new soil and your tree should perk up next yr and grow. Rember to prune down the tree accordingly. You have less root mass to supply the tree.

Your tree is probably so root bound that all the enegy it musters goes into fruit and not growth.

Extra cuttings can be rooted for extra trees.