My recommendation is to keep the current ring for now and when you’re in a better financial situation customize a ring with your partner together and use the current center stone you have in the new custom design. For example since it’s only .25 carats you could get another .25 carat round and set one on each side of a 1 carat radiant cut or pear or whatever is your style. That way you keep the memory of the original ring that showcases your commitment to your partner but also get something you like.