Can I repair speaker foam?

i take it that you dont want to replace the damaged speaker or send it off for a refoam job,you can buy a product called (vulkem)that will repair the tear,vulkem is a polyurathene sealent that comes in a standard sized caulking tube & it can be bought at most professional glass shops that sell high performance sealents,if your local glass shop dont have vulkem then ask for (sikaflex 1a) which is also a butyl based sealent that dries flexible.

both products should cost less than a $5 spot & they both come in colors that will half ass match your surround.

First find out how much is the whole driver or speaker.
Maybe it's not worth to put effort towards there man!