Pancreas enzyme issues and PancrePlus Powder?

Species: Dog, Mutt

Age: 6

Sex/Neuter status:Male neutered

Breed: Mutt, We think lab mix

Body weight: 50lbs when healthy

History: Summer of 2014 our mutt dog got some nasty, smelly, kinda orange-y runs. At first we thought it was from traveling, but when it didn't go away and he started losing weight despite eating his food we took him to the vet. They did lots of tests, but in the end weren't willing to do more in depth expensive tests even though I wanted them done. So we went to a new vet, who did a few tests and sent some blood work to a college and found out the problem. His pancreas wasn't making a digestive enzyme, he was pretty much starving to death even though we were feeding him extra. He's been on PancrePlus Powder since then, and everything was fine until last month.

Clinical signs: Really terrible unusual gas. Runny orange ish poos. Losing weight.

Duration: About a month and a half to 3 months

Your general location: SW Oklahoma/Texas

So pretty much my question is, does PancrePlus Powder lose effectiveness over time? / Do dogs get "resistant" to it? Does the dose need to be increased over time?

Over the holidays, christmas ish, we noticed our dog having the tell tell poos of his meds not working. I thought, maybe with traveling, we haven't been as good about giving it to him and/or letting it set on his food long enough. And in Jan I found out my husband forgets how much he's supposed to have and sometimes wasn't giving him enough meds. So part of Jan, and all of Feb I've been really strict on making sure he gets the meds int he right amount and it sets on his food for the right amount of time.

Well he's still having the runs, gas, and now it's obvious he's losing weight again. Before I take him to the vet, I wanted to know if it was just something that happens with PancrePlus Powder, that every now and then you need to increase the dose. I can and will take him in if he needs it, but we're trying to save money now because my husband is about to be unemployed with no job lined up yet. So if it's normal and I can just increase his dose that would be great. If not, and we need to have more blood work done or something, then that's what we'll do.