Hi mingmalefactor,
PVC are not dangerous in a structurally normal heart even when you are getting 1,000s a day. They are just VERY, VERY annoying. I'm sorry you are having them. Try to relax. Stress and worry and even being tired can make you have more. I'm sorry but I don't think there is any way to predict whether they'll increase. I find that mine (and I usually have PAC's) cycle. Sometimes they are horrible and many. Then I may not feel them for weeks. ????? No rhyme or reason. My cardiologist says they just do that and he suffers from them too. Neither of us take medication for it although they sometimes prescribe a beta blocker to lessen the feeling of them. The beta blockers do not reduce the number you will get though.
I quess you have been checked out by a doctor since you know that you are experiencing PVC's. ?????? If you haven't, you really do need to go see one just to make sure that is what you are having and not something else and to make sure your heart is structurally normal. Hopefully they will just cycle to the 'quiet phase' and stay there a good long time!!! 
(It's what we all HOPE for!!!!!!)