Forums Scripts & Popups replacing with wildcard

is there anyway i can replace a certain text with wildcard?
for example..

i have bla(+1) or bla(+30)
so i have a var for bla
and the user can choose what number to increase by.
but how would i replace it like bla(+*)
with also getting the number inside and adding it to the var %bla

hope you can understand that

thanks

its ok now ^_^
someone helped me!