I'm not sure exactly how you made the joint, do you have a photo? The way that I do it is to use a female fitting adapter, female threads by spigot fit (it's a hard fitting to find) so that I'm not "threading" the PVC into the acrylic. I use a router and template to rout a hole the exact size for the spigot fit adapter, then coat the fitting with weld-on #40, then push and twist into the hole, so the weld-on #40 really fills the joint. Still, I've had some leaks at those joints before, usually because I either didn't get enough #40 in the joint as opposed to on top of it, or I used weld-on #40 that was getting close to the expiration date. Your best option at this point, assuming you can't get it apart, would probably be to use a dremel and small file to get as much of the adhesive off the top of the joint as possible, really clean it up, and spread a thin layer of new weld-on #40 right around the joint. It would be helpful to use an aspirator (that's a syringe without the needle) to get the adhesive right where you want it. You also have to be very careful to make sure you get an accurate 20:1 ratio of resin to activator when mixing the #40. I've found an old salifert test kit that has the 5ml and 1ml syringes works well to get the measurements right.