To answer the question of value, you'd have to know the market for that particular model. (I do not.)
Is your pistol (as it sits now) something a collector/buyer would be very interested in, or is it more bottom-of-the-barrel (as far as what's generally available)? If the former, refinishing would harm its value significantly. If the latter, refinishing probably wouldn't affect its value (and in some cases could increase it).
But refinishing is almost always a net value loss proposition, because if you take a shooter-grade example, currently worth $600 (random number) and refinish it where someone would gladly pay $750, but the refinish work cost you $200 then you're actually down $50 (assuming you sell it soon). Obviously the longer you wait, the more the dollar value would increase.
Of course none of this matters if you never plan on selling it, so do what is best for you.
I bought a refinished TT-30 at what I thought was a good price. I paid less than poor condition originals go for, and tremendously less than a nice condition original would've cost. I wanted to shoot it, so there was no reason for me to pay $400 more for an original with all the bluing worn off. It's not going to spend its time with me in a display case, so I'd rather shoot a nice looking gun that appears the way it would've looked if you went back in time and grabbed one. That's just me. Maybe the guy I bought it from lost money, but I doubt it. He didn't seem to know anything about it being refinished, and whoever performed the work did an excellent job.