Not exactly sure, but if you are not rinsing well enough between samples, or particles of lime are picked up or disturbed on the contacts and eventually dissolve showing higher resistsnce (lower conductity).  10 readings seem excessive for stability, but unsure how you added lime and how you are sampling, adding water to soil or sampling water table or adding soil tomambeaker and mixing it up.  I dont know about any realignment of ions, the resistivity measures resistance to electrical current, higher resistance, purer water with fewer ions and cations to carry current.  If in sampling you are kicking in a bit of lime dust, and lowering probe, the lime dust will be temporarily concentrated in the probe and diluting to equilibrum, increasing restance.  This might be a possible explanation, but if the meter is jumping wildly about, I would check for a loose wire connection or faulty contact in probe or probe to instrument.  If you can borrow one or take a sample over to another lab, see if you have same result.