You need loads of repetition, and then eventually, speed building. I think it's quite hard to provide it all through worksheets and games at home for a child who needs more repetition. I would suggest going to the Power of 2 website and signing on for 1 2 3 maths and just doing the timestables book only. This will give repetition and look at both multiplication and division facts and not in the standard order. It will not do speed though - but of course it will build up speed incidentally. Then to build up speed sign on to Caro* Vorderma* Arithmetic School but start with the timestable module (you do have some control over the system) and then once that's done, do the modules which relate to multiplication and division. The homework is timed so children feel under pressure to complete in time. Also it's not very exciting so they soon learn it's best just to get it done as fast as possible.
If you don't want to spend money on the online stuff, try buying all the relevant workbooks from Schofield and Sims, Carol "orderman, Rigby Star etc and work your way through them - an Amazon search will get more and more refined and you'll see the wide range there is.
Or if you don't want to spend a thing, customize your own worksheets free of charge on www.johngom.com
Also, get the Percy Parker songs CD to listen to in the car. It probably won't help them remember the facts randomly though.