Cracked Invisalign retainer, can I still use it?

There is a crack in my upper invisalign retainer. Its covers about the whole front tooth. Is it ok to still wear it? I only had this for about four months and my family is in alittle financial issues. I am going to the dentist next week but they told me retainers are about five hundred dollars each. I don’t want to replace it. Is it possible to still use it or ask dentist to fix the original one??