>Is it possible to modify the signal from the sensor to be compatible with the analyzer using some electronics (resistors, etc).
Theoretically, yes, but practically, no.
A Pt1000 has exactly 10x the resistance of a Pt100 as the abbreviated temperature vs. resistance tables below show.
Steve Bailey's suggestion to wire ten Pt100's in series would work, assuming all the RTD's measure the same temperature point and the accumulated error of 10 sensor errors averages out (not necessarily a valid assumption). In fact, Siemens has a temperature transmitter whose configuration uses the wierd terminology of 'number of sensors', meaning how many multiples of "100 ohm sensors" are involved in the measurement (rather than 'what is the resistance of the element?).
The pH analyzer measures RTD temperature by driving a fixed current through the RTD circuit and measuring the voltage drop, usually compensating for lead wire resistance, then converting to temperature units. You'd have to alter the internal circuitry of the analyzer to change it for a Pt100, which isn't practical.
The wiring for the temp sensor in a pH probe are individual wires that are part of the pH probe's cable assembly. Presumably you could buy and substitute a commercial Pt1000 and do all mucking around with cables and connectors.