Man, that really sucks. I have no idea of any adhesive that you could use to stick the keel guard back on, and my guess is that doing so will compound the clean up process when the inevitable happens and you have to replace it. I've replaced the keel guard on my last two boats, and it takes some time and quite a bit of elbow grease, but can be done. I did the first one around six years ago, and it was still in good shape when I sold the boat last month. The second one, I finished last Friday. The adhesive on the keel guard is kind of like a thin double sided tape. What I've found works well is to peel the keel guard off and use a heat gun to heat the double sided foam type adhesive and scrape it off with a putty knife (carefully) about a foot at a time. When you are done with this process, you will still have the sticky adhesive from the other side of the double sided tape on the boat hull. I put acetone in a spray bottle and spray a couple of coats of acetone on the adhesive, again about a foot at a time and scrape the adhesive off (carefully) with a putty knife. I then soak a towel with a product called goo gone to remove the last of the adhesive. The process takes several hours, laying on your back under the boat. A new keel guard can be purchased at many fishing outlets, I bought mine at Cabelas. Installation of the new keel guard is pretty straight forward, just follow the manufacturers recommendations.